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  • American Institute of Physics (AIP)  (17)
  • International Union of Crystallography (IUCr)  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Absence of photoelectron spectroscopic evidence for "proton tunneling'' in the cation ground state of jet-cooled tropolone (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 9401-9403 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: From our high resolution REMPI threshold photoelectron measurements of jet-cooled tropolone, it has been found that no spectral doublet showing "proton tunneling'' in the cation ground state (D0) is observed within an experimental accuracy of 2 cm−1. The adiabatic ionization potential was obtained as Ia=68 365±5 cm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461168
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  • 2
    Electronic Resource
    Electronic Resource
    Reply to the Comment on: Cation vibrational spectroscopy of trans and gauche n-propylbenzene rotational isomers. Two-color threshold photoelectron study and ab initio calculations (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 5109-5109 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In connection with the Comment by Liu and Zhou [J. Chem. Phys. 98, 0000 (1993)] on our paper [J. Chem. Phys. 97, 2920 (1992)], the following can be pointed out. Although our ab initio calculations with the STO-2G basis set are not sufficient, we have obtained some useful information from symmetry consideration which supports our experimental vibrational assignments of the trans n-propylbenzene cation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464938
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  • 3
    Electronic Resource
    Electronic Resource
    Cation vibrational spectroscopy of trans and gauche n-propylbenzene rotational isomers. Two-color threshold photoelectron study and ab initio calculations (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 2920-2927 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper, a full account of an earlier report [Takahashi, Okuyama, and Kimura, J. Mol. Struct. 249, 47 (1991)] on the cation vibrational spectra of trans and gauche n-propylbenzene, which were obtained by means of a two-color (1+1') multiphoton ionization threshold photoelectron technique is presented. The trans and gauche cations were separately produced by (1+1') multiphoton ionization resonant through the S1 vibronic levels of n-propylbenzene in supersonic free jets in which both the trans and gauche isomers exist. From the observed threshold photoelectron spectra, adiabatic ionization energies are determined as Ia(trans)=70 278 cm−1 (8.7134 eV) and Ia(gauche)=70 420 cm−1 (8.7311 eV) with an accuracy of ±8 cm−1 (±1 meV). Furthermore, four benzene ring modes (6b+, 1+, 12+, and 18a+) as well as several low-frequency torsional and bending modes have been identified which are sensitive to the relative conformations of the n-propyl group with respect to the benzene ring [(trans)+: 82, 212, and 300 cm−1; (gauche)+: 46, 73, 207, and 252 cm−1]. The present vibrational assignments of the trans and gauche cations are based on a normal mode analysis performed for the trans cation by ab initio calculations. In the present work, this technique is demonstrated to be quite powerful for distinguishing the vibrational spectra of different cation isomers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463033
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  • 4
    Electronic Resource
    Electronic Resource
    A study of phenylacetylene and styrene, and their argon complexes PA–Ar and ST–Ar with laser threshold photoelectron spectroscopy (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 8926-8933 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this work, the molecules styrene (ST) and phenylacetylene (PA), as well as their argon complexes ST–Ar and PA–Ar, have been investigated with (1+1') resonance enhanced multiphoton ionization (REMPI) threshold photoelectron spectroscopy (TES). The first adiabatic ionization energies of ST, PA, ST–Ar, and PA–Ar have been measured as 68 267±5, 71 175±5, 68 151±5, and 71 027±5 cm−1, respectively. For both ST–Ar and PA–Ar, the first photoelectron band shows structure in the lowest frequency van der Waals (vdW) bending mode in the ground ionic state, with νvdW being measured as 15 cm−1 in each case. For each molecule excitation to a particular vibrational level of the S1 state followed by ionization, allows structure in that mode to be observed in the threshold photoelectron spectrum. This has been achieved for three modes in both styrene and phenylacetylene. The experimental ionic vibrational frequencies thus obtained, have been compared with those known for the S0 and S1 states.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463367
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  • 5
    Electronic Resource
    Electronic Resource
    The role of electronic and geometric factors in "proton tunneling:'' A comparative study of tropolone and 9-hydroxyphenalenone by threshold photoelectron spectroscopy (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 56-66 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: High resolution two-color threshold photoelectron spectra of tropolone and 9-hydroxyphenalenone (9-HPO) isolated in a free jet expansion have been measured to study the proton tunneling phenomena in the cation ground state (D0). The tunneling splitting widths of the D0 zeroth vibrational level for the both molecules lie within our experimental accuracy (2 cm−1), indicating that the proton tunneling is inhibited when compared to that obtained in their respective neutral states. By means of a comparative study of these two molecules, the tunneling inhibition has been explained in terms of a large contribution from the electronic factor which represents the changes in charge distribution of the π electrons upon ionization. The geometric factor, which is associated with the ring planarity is less important in determining the rate of tunneling in the D0 state. In the case of tropolone, we have found that the measurement of an out-of-plane skeletal vibration in various electronic states make it possible to describe the tunneling path at a higher level than a simple one-dimensional description. Moreover, the adiabatic ionization energies of 9-HPO and the deuterated 9-HPO have been determined accurately to be 65 338±5 cm−1 (8.1009±0.0006 eV) and 65 350±5 cm−1 (8.1024±0.0006 eV), respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465783
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  • 6
    Electronic Resource
    Electronic Resource
    Vibrational spectra of aniline–Arn van der Waals cations (n=1 and 2) observed by two-color "threshold photoelectron'' [zero kinetic energy (ZEKE)-photoelectron] spectroscopy (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 6399-6406 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Measurements of mass-selected ion-current and threshold photoelectron spectra of jet-cooled aniline–Arn van der Waals complexes (n=1 and 2) have been carried out with a two-color resonantly enhanced multiphoton ionization (REMPI) technique using a high-resolution threshold photoelectron analyzer developed in this laboratory. From our (1+1') REMPI experiments via the respective excited S1 states, we have obtained photoelectron spectra with well-resolved vibrational progressions due to "low-frequency van der Waals modes'' of the cations; νvdW=16 cm−1 (n=1) and νvdW=11 cm−1 (n=2). From Franck–Condon calculations, we have assigned these low-frequency vibrations to the "van der Waals bending'' of the cations. We have also found that the angles of the van der Waals bonds in the cations are changed by 8.2 (n=1) and 8.8 (n=2) degrees with respect to the S1 states. The adiabatic ionization potentials (Ia) of aniline and the aniline–Arn complexes (n=1 and 2) have been determined as 62 268±4 cm−1 (aniline), 62 157±4 cm−1 (n=1), and 62 049±4 cm−1 (n=2). Their shifts ΔIa are 111 cm−1 (n=1) and 219 cm−1 (n=2) with respect to aniline. Spectral shifts due to complex formation have been observed for a total of 13 ring modes of the cations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462634
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  • 7
    Electronic Resource
    Electronic Resource
    Status of the UVSOR Facility−1991 : Proceedings of the 4th international conference on synchrotron radiation instrumentation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 1584-1585 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: At the UVSOR Facility, a 750-MeV storage ring has been operated with an initial current of 200 mA. It has two undulators and a superconducting wiggler. A computer control system with two VAXs was introduced. The bunch length at the single-bunch operation was studied. A gain measurement for free electron laser study was successfully done. The number of beam lines is 19. By the use of these beam lines, about 140 programs have been accomplished in the fiscal year 1990. Among them, a photoelectron coincidence study on Xe atoms, a Te 4d absorption study in p- and n-type SnTe, and a photostimulated desorption study of Na atoms from sodium halides are demonstrated as topics. The Department of Vacuum Ultraviolet Photoscience has been newly approved at IMS to impel the researches by using UVSOR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142982
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  • 8
    Electronic Resource
    Electronic Resource
    The role of zinc pre-exposure in low-defect ZnSe growth on As-stabilized GaAs (001) (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 939-941 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Zinc coverage and the structures of Zn-exposed As-stabilized GaAs(001)-(2×4) and -c(4×4) surfaces have been studied using x-ray photoelectron spectroscopy and scanning tunneling microscopy in order to clarify the role of the Zn pre-exposure process in ZnSe growth on GaAs(001). Since Zn atoms stick on the GaAs-(2×4) surface even though their interaction is very weak, Zn may act as a balancer to form a neutral ZnSe/GaAs interface. Zn can also remove excess As atoms and make a "pure" (2×4) structure that is the only possible starting surface for low-defect ZnSe heteroexpitaxy on a GaAs(001) surface. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122045
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  • 9
    Electronic Resource
    Electronic Resource
    Improvement of far-field pattern in nitride laser diodes (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 2960-2962 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have clearly demonstrated a single spot in a far-field pattern of nitride-based laser diodes with a thick n-AlGaN layer/low-temperature-deposited buffer layer/sapphire. This AlGaN-based structure has realized a crack-free 1-μm-thick n-type Al0.06Ga0.94N cladding layer, leading to suppression of optical leakage from the waveguide region to the underlying layer and improvement of optical confinement. The threshold current of the laser diode is about 230 mA, which is comparable to or better than that of our laser diodes with the conventional GaN-based structure. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125201
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  • 10
    Electronic Resource
    Electronic Resource
    Atomic nitrogen doping in p-ZnSe molecular beam epitaxial growth with almost 100% activation ratio (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 1077-1079 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An almost 100% activation ratio {(NA-ND)/[N]} for a nitrogen-doped ZnSe molecular beam epitaxy (MBE) layer with the highest net acceptor concentration (NA-ND) of 1.2×1018 cm−3 was obtained using a high-power rf plasma source. Even at this high NA-ND value, a 4.2 K photoluminescence spectrum shows bound exciton emission and deep donor–acceptor pair emission with well-resolved phonon replicas. The high activation in nitrogen doping could be ascribed to the generation of the predominant atomic nitrogen and to the suppressed extraction of nitrogen ions and excited neutral nitrogen molecules due to the structure of the orifice placed between the MBE growth chamber and the plasma discharge tube of the high-power plasma source. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.119733
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