ALBERT

Description: We present an overview of recent results on optical coherence tomography with the use of extreme ultraviolet and soft X-ray radiation (XCT). XCT is a cross-sectional imaging method that has emerged as a derivative of optical coherence tomography (OCT). In contrast to OCT, which typically uses near-infrared light, XCT utilizes broad bandwidth extreme ultraviolet (XUV) and soft X-ray (SXR) radiation (Fuchs et al in Sci Rep 6:20658, 2016). As in OCT, XCT’s axial resolution only scales with the coherence length of the light source. Thus, an axial resolution down to the nanometer range can be achieved. This is an improvement of up to three orders of magnitude in comparison to OCT. XCT measures the reflected spectrum in a common-path interferometric setup to retrieve the axial structure of nanometer-sized samples. The technique has been demonstrated with broad bandwidth XUV/SXR radiation from synchrotron facilities and recently with compact laboratory-based laser-driven sources. Axial resolutions down to 2.2 nm have been achieved experimentally. XCT has potential applications in three-dimensional imaging of silicon-based semiconductors, lithography masks, and layered structures like XUV mirrors and solar cells.

Description: The two-dimensional multi-angle light scattering (2D-MALS) technique has been extended for single-shot size measurements of soot aggregates in flames. Six cameras are used for instantaneous acquisition of the elastic scattering from the aggregates at different directions between 10 to 90$$^circ$$ ∘ of a laser light sheet. Two diluted ethylene (50 and 60% by volume of $$hbox {C}_2hbox {H}_4$$ C 2 H 4 fuel diluted with inert $$hbox {N}_2$$ N 2 ) coflow laminar diffusion flames with little flickering are used as proof of concept. Results of instantaneous, average and fluctuating 2D fields of the effective radii of gyration, which are expected to characterize the size of the aggregates, compare well with the literature, demonstrating the applicability of the proposed sizing method to weakly unsteady combustion processes.

Description: We experimentally characterize the positions of the diffraction maxima of a phase grating on a screen, for laser light at oblique incidence (so-called off-plane diffraction or conical diffraction). We discuss the general case of off-plane diffraction geometries and derive basic equations for the positions of the diffraction maxima, in particular for their angular dependence. In contrast to previously reported work (Jetty et al. in Am J Phys 80:972, 2012), our reasoning is solely based on energy- and momentum conservation. We find good agreement of our theoretical prediction with the experiment. A detailed discussion of the diffraction maxima positions, the number of diffraction orders, and the diffraction efficiencies is provided. We assess the feasibility of an experimental test of the phenomenon for neutron matter waves.

Description: We present detailed experimental results with cryogenic Yb:YLF gain media in rod-geometry. We have comparatively investigated continuous-wave (cw) lasing and regenerative amplification performance under different experimental conditions. In the cw lasing experiments effect of crystal doping, cw laser cavity geometry and pump wavelength on lasing performance were explored. Regenerative amplification behavior was analyzed and the role of depolarization losses on performance was investigated. A recently developed temperature estimation method was also employed for the first time in estimating average crystal temperature under lasing conditions. It is shown that the thermal lens induced by transverse temperature gradients is the main limiting factor and strategies for future improvements are discussed. To the best of our knowledge, the achieved results in this study (375 W in cw, and 90 W in regenerative amplification) are the highest average powers ever obtained from this system via employing the broadband E//a axis.

Description: We report on the formation of various intensity pattern types in detuned Fourier domain mode-locked (FDML) lasers and identify the corresponding operating conditions. Such patterns are a result of the complex laser dynamics and serve as an ideal tool for the study of the underlying physical processes as well as for model verification. By numerical simulation we deduce that the formation of patterns is related to the spectral position of the instantaneous laser lineshape with respect to the transmission window of the swept bandpass filter. The spectral properties of the lineshape are determined by a long-term accumulation of phase-offsets, resulting in rapid high-amplitude intensity fluctuations in the time domain due to the narrow intra-cavity bandpass filter and the fast response time of the semiconductor optical amplifier gain medium. Furthermore, we present the distribution of the duration of dips in the intensity trace by running the laser in the regime in which dominantly dips form, and give insight into their evolution over a large number of roundtrips.

Description: A THz-pulse-driven compact, 

Description: The splash created by intense laser pulse impact onto a liquid tin layer is studied experimentally using time-delayed stroboscopic shadowgraphy. An 8-ns infrared (1064 nm) laser pulse is focused onto a deep liquid tin pool. Various laser spot sizes (70, 120, and 130 $$upmu$$ μ m in diameter) and various laser pulse energies (ranging 2.5–30 mJ) are used, resulting in laser fluences of $$sim$$ ∼  10–1000 J/cm$$^2$$ 2 inducing pronounced splashing. Specifically, we study the time evolution of the splash crown-width. The crown width expansion velocity is found to be linearly dependent on the laser energy, and independent of the focal spot size. A collapse of all crown width evolution data onto a single master curve confirms that the hydrodynamic evolution of our laser-impact-induced splash is equivalent to droplet-impact-induced splashing. Laser-impact splashing is particularly relevant, e.g. for high-brightness laser-assisted discharge-produced plasma and laser-produced plasma sources of extreme ultraviolet light for nanolithography.

Description: Fluorescence spectra and lifetimes of anisole and toluene vapor in nitrogen have been measured at conditions below ambient (257–293 K and 100–2000 mbar) upon excitation with 266-nm laser light to expand the applicable range of anisole and toluene laser-induced fluorescence (LIF) for conditions below room temperature that occur in expanding flows and cases with strong evaporative cooling. Anisole fluorescence spectra broaden with decreasing pressure while fluorescence lifetimes decrease simultaneously. This is consistent with a more pronounced effect of internal vibrational redistribution on the overall fluorescence signal and can be explained by significantly reduced collision rates. In the case of toluene, the transition from photo-induced heating to photo-induced cooling was observed for the first time for 266 nm. The data confirm predictions of earlier work and is particularly important for the advancement of the available photo-physical (step-ladder) models: since those transitions mark points where the molecules are already thermalized after excitation (i.e., no vibrational relaxation occurs during deactivation), they are important support points for fitting empirical parameters and allow analytical determination of the ground state energy transferred to the excited state. The data enable temperature and/or pressure sensing, e.g., in accelerating cold flows using laser-induced fluorescence of both tracers.

Description: In the analysis of complex stratigraphical structures like painted artefact, infrared (IR) techniques can provide precious information about elements hidden under superficial layers of the artwork, such as pictorial features and structural defects. This paper presents a novel complementary use of reflectographic and thermographic techniques for the survey of three baroque paintings, preserved at the Chigi Palace in Ariccia (Italy). First, the IR-ITR laser scanner prototype has been used for the preliminary and remote near-IR reflectographic survey of the areas where the canvas was located. The resulting map was then used for planning the thermographic and mid-IR reflectographic studies, focusing the analyses on the most interesting areas of one of the paintings, called “La Primavera”. The combination of the three imaging techniques revealed several details not visible by the naked eye, such as restored lacunas and pentimenti, demonstrating the validity and complementarity of the proposed combined methodologies.

Description: In this work, we have investigated six different in situ optical contactless temperature probing methods for cryogenic Yb:YAG systems. All the methods are based on variation of fluorescence spectra with temperature, and they either look at the width of the emission line, the ratio of the emission intensity at different wavelengths and to the overall spectral change at selected wavelength intervals. We have shown that, for Yb:YAG crystal with homogeneous temperature distribution, one can perform real-time contactless optical temperature measurements with a ± 1 K accuracy in the 78–300 K range. We have further tested the methods in measuring the average temperature of Yb:YAG rods at up to 500 W absorbed pump power level. We have seen that, a real-time temperature measurement accuracy of ± 5 K is feasible in both lasing and non-lasing situations for estimating the average temperature of crystals under nonhomogeneous thermal load. The techniques are quite valuable in evaluating the bonding quality of Yb:YAG crystals in cryogenic systems. Moreover, the real-time temperature information provides feedback on parameters like cavity alignment status and extraction efficiency to the laser engineers while optimizing the system.

Description: A one-dimensional premixed ethylene–air flame is investigated regarding the presence of various combustion intermediates and products relevant for the formation of carbonaceous particles for various equivalence ratios and spatial positions using in situ UV–Vis absorption spectroscopy. A laser driven light source in combination with a fast spectrometer allow to record absorption spectra at a high rate required for practical combustion devices. The approach is coupled with a least squares regression procedure using a database of several absorbing species in the flame. To account for the high temperature flame conditions, the absorption spectra are convoluted by a simplified Maxwell–Boltzmann distribution model. While the approach is based on several assumptions and a verification requires future detailed intercomparison with other techniques, a first semi-quantitative evaluation can be obtained. This novel approach opens a potential route to the in situ measurement of the evolution of polycyclic aromatic hydrocarbons (PAHs) in flames.

Description: This article presents a critical look at the standard theory of bright and dark photorefractive screening solitons. We pay attention to the commonly overlooked fact of the inconsistency of the theory in the context of the accordance of soliton solution with the microscopic band transport models. Taking into account the material equations for the semi-insulating semiconductor (SI-GaAs) and including the nonlinear transport of hot electrons, a simple differential equation has been developed to determine the distribution of refractive index changes in the material for a localized optical beam. An amendment to the standard solution of (1 + 1)D solitons has been proposed, which particularly should be used for dark solitons to obtain the plausible self-consistent solutions

Description: We report the three-dimensional (3D) mapping of polycyclic aromatic hydrocarbons (PAHs), soot, and hydroxyl radicals (OH) in ethylene/air diffusion flames. A structured illumination-based frequency recognition algorithm for multiple exposures (FRAME) approach is combined with sample translation to intersect the flame in several two-dimensional planes. The FRAME technique has been used for recording a snapshot of multiple species on a single camera. It relies on extracting the amplitude of spatial modulation of two or more probed species encoded on a single sub-image. Here, the FRAME technique is first applied for simultaneous imaging of PAH by laser-induced fluorescence (PAH-LIF) and soot by laser-induced incandescence (LII). Sequentially, it is employed for simultaneous mapping of OH-LIF and soot-LII. The LII signal is converted to absolute soot volume fraction (fv) maps using a line-of-sight light extinction measurement. Finally, we have demonstrated the approach for layer-wise 2D imaging of soot volume fraction and averaged 3D mapping of multiple species.

Description: An extensive set of LII signals measured in a Diesel spray flame has been simulated using a refined LII model built upon a comprehensive version of soot heat- and mass-balance equations. This latter includes terms standing for saturation of linear, single- and multi-photon absorption processes, cooling by sublimation, conduction, radiation and thermionic emission in addition to mechanisms depicting soot oxidation and annealing, non-thermal photodesorption of carbon clusters as well as corrective factors allowing considering shielding effect and multiple scattering (MS) within aggregates. A complete parameterization of the so-proposed model has been achieved by means of an advanced optimization procedure coupling design of experiments with a genetic algorithm-based solver. Doing so, the values of different factors involved in absorption and sublimation terms have been assessed for a 1064-nm laser excitation wavelength including the multi-photon absorption cross section for C2 photodesorption and the saturation coefficients for linear- and multi-photon absorption, among others. This parameterized model has then been demonstrated to effectively reproduce signals measured in different combustion media including a CH4/O2/N2 premixed flat flame and a diffusion ethylene flame. As a result of the data derived from the analysis of the Diesel flame, a thermal accommodation coefficient value of 0.49 has been assessed against 0.34 when neglecting the shielding effect. In addition, values of the soot absorption function ($$Eleft( m ight)$$ E m ) comprised between 0.18 and 0.31 have been inferred depending on the particle maturation stage. On the other hand, $$Eleft( m ight)$$ E m 24% higher on average have been estimated when neglecting MS thus illustrating the importance of aggregate characteristics on soot properties derived through LII modeling. Eventually, the $$Eleft( m ight)$$ E m evolution observed herein has been compared with results issued from studies conducted with varied hydrocarbons which led to highlight the crucial role played by the soot maturity level over the nature of the burnt fuel as far as optical properties are concerned.

Description: The conversion of transverse mode-locked (TML) laser beams from a Hermite-Gaussian (HG) to a Laguerre-Gaussian (LG) mode set using a cylindrical lens mode converter was demonstrated experimentally. By changing the spatial symmetry of the beams new spatio-temporal dynamics for TML lasers were enabled. In particular, the fast linear motion of an oscillating laser spot, generated by a TML laser based on HG modes, was translated into the circular motion of a TML laser beam based on LG modes. The mode conversion was demonstrated successfully for different average mode orders. Apart from an average ellipticity of about $$6\%$$ 6 % , the converted beam profiles remained circular over the propagation from the near- into the far-field. The remaining ellipticity seemed to be introduced by astigmatism of the incident HG TML beam, which could be compensated before conversion. Due to their radial symmetry and high scanning speed TML laser beams based on LG modes are well suited for precision applications like STED or Minflux microscopy.

Description:    The photoluminescence properties of alkali-earth magnesium silicates (M 2 MgSi 2 O 7 , M=Ca, Sr, and Ba) doped with Eu 2+ were investigated. Solid solutions of Ba x Sr 2− x Si 2 O 7 , Ca 2 MgSi 2 O 7 , and Sr 2 MgSi 2 O 7 were prepared. Ba x Sr 2− x Si 2 O 7 retained a tetragonal crystal structure similar to the structure of the other compounds up to a stoichiometry of x =1.6, which enabled a systematic study of the common structure. Monoclinic Ba 2 MgSi 2 O 7 was prepared, and the luminescence properties were compared with those of other samples. The emission and excitation spectra of tetragonal M 2 MgSi 2 O 7 (M=Ca, Sr, and Ba) changed as a function of the covalency, site symmetry, and crystal field strength. The luminescence properties showed excellent agreement with theoretical predictions based on these factors. The Stokes shift differentiated the emission behaviors of the tetragonal and monoclinic structures. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-4914-z Authors T. Kim, Department of Materials Science and Engineering, Seoul National University, Seoul, 151-742 Republic of Korea Y. Kim, Department of Materials Science and Engineering, Seoul National University, Seoul, 151-742 Republic of Korea S. Kang, Department of Materials Science and Engineering, Seoul National University, Seoul, 151-742 Republic of Korea Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We present a novel approach to extend optical coherence tomography (OCT) to the extreme ultraviolet (XUV) and soft X-ray (SXR) spectral range. With a simple setup based on Fourier-domain OCT and adapted for the application of XUV and SXR broadband radiation, cross-sectional images of semiconductors and organic samples becomes feasible with current synchrotron or laser-plasma sources. For this purpose, broadband XUV radiation is focused onto the sample surface, and the reflected spectrum is recorded by an XUV spectrometer. The proposed method has the particular advantage that the axial spatial resolution only depends on the spectral bandwidth. As a consequence, the theoretical resolution limit of XUV coherence tomography (XCT) is in the order of nanometers, e.g., 3 nm for wavelengths in the water window (280–530 eV). We proved the concept of XCT by calculating the reflectivity of one-dimensional silicon and boron carbide samples containing buried layers and found the expected properties with respect to resolution and penetration depth confirmed. Content Type Journal Article Category Rapid Communication Pages 1-7 DOI 10.1007/s00340-012-4934-8 Authors S. Fuchs, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany A. Blinne, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany C. Rödel, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany U. Zastrau, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany V. Hilbert, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany M. Wünsche, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany J. Bierbach, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany E. Frumker, Joint Laboratory for Attosecond Science, National Research Council of Canada and University of Ottawa, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada E. Förster, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany G. G. Paulus, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Next-generation laser diode arrays with integrated ‘on-chip’ volume holographic gratings can provide high power with spectrally narrowed output that can be tuned about the rubidium D 1 line—without causing significant changes to the laser’s flux or spectral profile. These properties were exploited to independently evaluate the effects of varying the laser centroid wavelength and power on batch-mode Rb/ 129 Xe spin-exchange optical pumping (SEOP) as functions of xenon partial pressure and cell temperature. Locally optimized SEOP was often achieved with the laser tuned to either the red or blue side of the Rb D 1 line; global optimization of SEOP was observed at lower cell temperatures and followed the D 1 absorption profile, which was asymmetrically broadened and red-shifted from the nominal wavelength. The complex dependence of the optimal wavelength for laser excitation on the cell temperature and Xe density appears to result from an interplay between cell illumination and the Rb/ 129 Xe spin-exchange rate, as well as [Xe] cell -dependent changes to the Rb absorption lineshape that are in qualitative agreement with expectations based on previous work [Romalis et al., Phys. Rev. A, 56:4569–4578, ( 1997 )], but significantly greater in magnitude. These next-generation lasers provide a ∼2–3-fold improvement in 129 Xe polarization compared to conventional broadband lasers. Content Type Journal Article Category Invited Paper Pages 1-14 DOI 10.1007/s00340-012-4924-x Authors N. Whiting, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, IL 62901, USA P. Nikolaou, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, IL 62901, USA N. A. Eschmann, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, IL 62901, USA M. J. Barlow, Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, NG7 2RD UK R. Lammert, QPC Lasers Division, Laser Operations LLC, Sylmar, CA 91342, USA J. Ungar, QPC Lasers Division, Laser Operations LLC, Sylmar, CA 91342, USA W. Hu, QPC Lasers Division, Laser Operations LLC, Sylmar, CA 91342, USA L. Vaissie, QPC Lasers Division, Laser Operations LLC, Sylmar, CA 91342, USA B. M. Goodson, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, IL 62901, USA Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We theoretically and experimentally investigate the Fraunhofer diffraction pattern of a vortex beam passing through an annular ellipse aperture. It is found that the pattern of the far-field diffraction intensity distribution exhibits some dark spots, which become clearer with increasing the value of the ellipticity factor of the annular ellipse aperture. The diffraction phenomenon is more obvious with increasing the value of the ratio of the inner long axis (or short axis) to the outer side of the annular ellipse aperture. The number of the dark spots in the Fraunhofer diffraction intensity distribution is just equal to the topological charge value of the measured optical vortex, and the centre of each dark spot is just a phase-singularity point. Based on this property, we can measure the topological charge of an optical vortex beam. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-4911-2 Authors H. Tao, College of Information Science and Engineering, Institute of Optics and Photonics, Huaqiao University, Xiamen, Fujian 361021, China Y. Liu, College of Information Science and Engineering, Institute of Optics and Photonics, Huaqiao University, Xiamen, Fujian 361021, China Z. Chen, College of Information Science and Engineering, Institute of Optics and Photonics, Huaqiao University, Xiamen, Fujian 361021, China J. Pu, College of Information Science and Engineering, Institute of Optics and Photonics, Huaqiao University, Xiamen, Fujian 361021, China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Eu 3+ and Sm 3+ co-doped molybdate phosphors have been synthesized via hydrothermal method. The phosphors have the advantages of narrower particle size distribution and regular homogeneous shape. The luminescent properties of the molybdate phosphors were systematically studied. The introduction of Sm 3+ into the red-emitting phosphors can generate a strong excitation line at 405 nm, originating from the 6 H 5/2 → 4 K 11/2 transition of Sm 3+ , significantly extending the excitation region for matching the near-ultraviolet light-emitting diodes (−400 nm). Energy transfer from Sm 3+ to Eu 3+ was observed. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-4916-x Authors X.-j. Geng, School of Materials and Metallurgy, Northeastern University, Shenyang, 110004 P.R. China Y.-w. Tian, School of Materials and Metallurgy, Northeastern University, Shenyang, 110004 P.R. China Y.-j. Chen, College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang, 110142 P.R. China L.-j. Xiao, College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang, 110142 P.R. China Y. Xie, College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang, 110142 P.R. China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We study pump requirements to produce femtosecond X-ray laser pulses at saturation from inner-shell transitions in the amplified spontaneous emission regime. Since laser-based betatron radiation is considered as the pumping source, we first study the impact of the driving laser power on its intensity. Then we investigate the amplification behavior of the K- α transition of nitrogen at 3.2 nm (395 eV) from radiative transfer calculations coupled with kinetics modeling of the ion population densities. We show that the saturation regime may be experimentally achieved by using PW-class laser-accelerated electron bunches. Finally, we show that this X-ray laser scheme can be extended to heavier atoms and we calculate pump requirements to reach saturation at 1.5 nm (849 eV) from the K- α transition of neon. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-4912-1 Authors M. Ribière, CEA, DAM, GRAMAT, 46500 Gramat, France S. Sebban, LOA, ENSTA ParisTech, Ecole Polytechnique, UMR CNRS 7639, Chemin de la Hunière, 91761 Palaiseau, France S. Jacquemot, LULI, Ecole Polytechnique, CEA, UPMC Université Paris VI, 91128 Palaiseau, France B. G. Chéron, CORIA, UMR, CNRS 6614, Saint Etienne du Rouvray, 76801 France K. Ta Phuoc, LOA, ENSTA ParisTech, Ecole Polytechnique, UMR CNRS 7639, Chemin de la Hunière, 91761 Palaiseau, France J. Gautier, LOA, ENSTA ParisTech, Ecole Polytechnique, UMR CNRS 7639, Chemin de la Hunière, 91761 Palaiseau, France J. Grunenwald, CEA, DAM, GRAMAT, 46500 Gramat, France P. Ribeiro, CEA, DAM, GRAMAT, 46500 Gramat, France M. Kozlova, LOA, ENSTA ParisTech, Ecole Polytechnique, UMR CNRS 7639, Chemin de la Hunière, 91761 Palaiseau, France P. Zeitoun, LOA, ENSTA ParisTech, Ecole Polytechnique, UMR CNRS 7639, Chemin de la Hunière, 91761 Palaiseau, France A. Rousse, LOA, ENSTA ParisTech, Ecole Polytechnique, UMR CNRS 7639, Chemin de la Hunière, 91761 Palaiseau, France Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    The production of ions via laser ablation for the loading of radiofrequency (RF) ion traps is investigated using a nitrogen laser with a maximum pulse energy of 0.17 mJ and a peak intensity of about 250 MW/cm 2 . A time-of-flight mass spectrometer is used to measure the ion yield and the distribution of the charge states. Singly charged ions of elements that are presently considered for the use in optical clocks or quantum logic applications could be produced from metallic samples at a rate of the order of magnitude 10 5 ions per pulse. A linear Paul trap was loaded with Th + ions produced by laser ablation. An overall ion production and trapping efficiency of 10 −7 to 10 −6 was attained. For ions injected individually, a dependence of the capture probability on the phase of the RF field has been predicted. In the experiment this was not observed, presumably because of collective effects within the ablation plume. Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-012-4884-1 Authors K. Zimmermann, Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany M. V. Okhapkin, Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany O. A. Herrera-Sancho, Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany E. Peik, Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We have demonstrated proof-of-principle of an incoherent ArF ∗ emission source with a quasi-point emission geometry using a laser-produced plasma in an Ar/F 2 /He/Ne mixed gas. The VUV emission characteristics, such as the emission size, were dependent on those of the plasma-initiating laser. The average emission power was 10 μW at a repetition rate of 10 Hz at 193 nm. The average power conversion efficiency of the 193-nm emission from the plasma-initiating Nd:YAG laser was 6.3×10 −6 . The average emission power at 193 nm was proportional to that of the plasma-initiating laser, indicating the scaling of the emission source. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-4906-z Authors M. Kaku, Department of Electrical and Electronic Engineering and Photon Science Center, University of Miyazaki, Gakuen Kibanadai Nishi 1-1, Miyazaki, 889-2192 Japan Y. Sato, Department of Electrical and Electronic Engineering and Photon Science Center, University of Miyazaki, Gakuen Kibanadai Nishi 1-1, Miyazaki, 889-2192 Japan S. Kubodera, Department of Electrical and Electronic Engineering and Photon Science Center, University of Miyazaki, Gakuen Kibanadai Nishi 1-1, Miyazaki, 889-2192 Japan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Measurements of 3-pentanone fluorescence quantum yield (FQY) over a wide range of temperatures and pressures in air and nitrogen bath gases are reported and a comprehensive FQY model in support of quantitative planar laser-induced fluorescence diagnostics at elevated pressures and temperatures is presented. Measurements were made of the FQY for 20 mbar of 3-pentanone in nitrogen and air for pressures between 1 and 25 bar in a high-pressure and high-temperature cell for excitation wavelengths of 248, 266, 277, and 308 nm. The measurements were performed in nitrogen from 298 to 745 K and in air from 298 to 567 K. The 3-pentanone FQY data were used to optimize FQY model parameters, including the oxygen and nitrogen quenching rates and vibrational relaxation cascade parameters for nitrogen and oxygen. This work introduces vibrational energy dependence for cascade parameters, as well as a nitrogen quenching rate. The new 3-pentanone FQY model agrees with the measurements within 10%, as well as with fluorescence signal measurements from optical internal combustion engines at pressures and temperatures up to 28 bar and 1100 K. Content Type Journal Article Pages 1-14 DOI 10.1007/s00340-012-4901-4 Authors B. H. Cheung, High Temperature Gasdynamics Laboratory, Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA R. K. Hanson, High Temperature Gasdynamics Laboratory, Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Through the study of photoluminescence spectra, fluorescence decay curves, concentration-dependent luminescence and low temperature luminescence, the energy transfer from isolated group to Yb 3+ is investigated in Yb 3+ doped YP 0.9 V 0.1 O 4 . The experimental results show that the energy transfer from group to Yb 3+ is very efficient. Cooperative energy transfer, through which one high-energy photon absorbed by group is converted to two near-infrared photons emitted by Yb 3+ ions, is proposed to be the energy transfer process. This efficient ultra-violet to near-infrared downconversion could have potential application in improving the efficiency of silicon-based solar cell. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-4892-1 Authors X. T. Wei, Department of Physics, University of Science and Technology of China, Hefei, 230026 China G. Jiang, Department of Physics, University of Science and Technology of China, Hefei, 230026 China K. Deng, Department of Physics, University of Science and Technology of China, Hefei, 230026 China C. Duan, Department of Physics, University of Science and Technology of China, Hefei, 230026 China Y. Chen, Department of Physics, University of Science and Technology of China, Hefei, 230026 China M. Yin, Department of Physics, University of Science and Technology of China, Hefei, 230026 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171