ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • American Institute of Physics (AIP)  (14)
Collection
Publisher
Years
  • 1
    Electronic Resource
    Electronic Resource
    Direct determination of long-range inverse-power potential coefficients from spectroscopic data (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 3479-3495 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: This paper presents and tests a method for determining the set of inverse-power coefficients defining the long-range potential tail of a given molecular state by least-squares fitting directly to the energies and inertial rotational constants (Bv 's) of vibrational levels lying very near dissociation. This approach is superior to the widely used procedure of determining potential points by some inversion procedure and fitting them to the inverse-power form, in that the fit is directly sensitive to the uncertainties in the experimental quantities, and that the parameter uncertainties due to interparameter correlation are greatly reduced. Moreover, the new method gives direct estimates of the number, energies, and other properties of unobserved levels lying above those being fitted. Improved results, including potential parameters up to C10, are presented for the B(3Π+0u) state of I2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459769
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Determining repulsive potentials of InAr from oscillatory bound→continuum emission (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 140-149 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Oscillatory bound→continuum emission from vibrational levels v'=0–6 of the B(2Σ+) state of InAr onto the repulsive walls of the X1(2Π1/2), X2(2Π3/2), and A(2Σ+) electronic states, has been measured. In the B(2Σ+)→X1(2Π1/2) spectrum, the intensity extrema have been associated with particular extrema and nodes of the radial wave functions of the emitting levels, and the resulting phase vs energy information directly inverted to yield a pointwise potential for the X1(2Π1/2) state. Analysis of the observed peak heights then showed that on the range 2.9–3.8 A(ring) the associated transition moment function is constant. The overlapping of the B(2Σ+)→X2(2Π3/2) and B(2Σ+)→A(2Σ+) spectra prevents application of the above inversion procedure, but reliable estimates of these two final-state potentials were obtained by matching quantum mechanical simulated spectra with experiment. The simulations also showed that the transition moment functions associated with all three transitions are of approximately equal strength.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464663
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Near-dissociation expansions and dissociation energies for Mg+–(rare gas) bimers (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 10217-10228 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: This paper describes the use of fits to near-dissociation expansions (NDE's) for performing optimum vibrational level energy extrapolations to determine diatom dissociation energies, together with realistic estimates of the uncertainties due to model-dependence. The imposition of extended near-dissociation theory constraints on the leading deviation from limiting near-dissociation behavior is introduced and applied for the first time. Fits of recently determined vibrational energies for Mg+–Ar, Mg+–Kr, and Mg+–Xe to near-dissociation expansions yield improved estimates of the dissociation energies and realistic predictions for the total number and extrapolated energies of upper vibrational levels for both the A 2Π and X 2Σ+ states. A combined analysis of the data for the A 2Π1/2 and 2Π3/2 states, and of the vibrationally-dependent spin–orbit splittings, yields particularly compact internally consistent results for these systems. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467902
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Infrared spectrum and potential energy surface of He–CO (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 39-61 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: For 3He–CO and 4He–CO van der Waals bimers, fully resolved infrared spectra in the 4.7 μm region near the fundamental band origin of the CO monomer have been measured for the first time. Only a small fraction of the observed lines could be assigned using conventional empirical spectroscopic techniques, and little additional insight was gained from synthetic spectra generated from a published ab initio potential for this system. However, a complete set of unique assignments was made on the basis of comparisons with synthetic spectra generated from a variety of trial potential energy surfaces, and least-squares fits to the observed transition frequencies were used to determine a new anisotropic potential energy surface for this system. This new surface is much deeper and has a much stronger well depth anisotropy than the best previous one, and its predictions of very low temperature microwave line broadening cross sections raise serious questions regarding the methodology for calculating that property.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468147
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Linewidths and shifts of very low temperature CO in He: A challenge for theory or experiment? (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 4005-4014 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The pressure broadening and shifting coefficients for pure rotational transitions of CO in a He bath gas at very low temperatures are calculated from the best available potential energy surfaces, and compared with very recent measurements by M. M. Beaky, T. M. Goyette, and F. C. De Lucia [J. Chem. Phys. 105, 3994 (1996)]. The results obtained for two recent empirical potentials determined from fits to Van der Waals spectra, and for a recent high quality purely ab initio surface, are consistent with one another. The best of the spectroscopic potentials also yields good agreement with high temperature virial coefficients and transport properties. Predictions from all three of these potentials agree with linebroadening and shifting measurements at temperatures above ∼20 K, but are in substantial disagreement with the measurements at temperatures below 4 K. At present, the source of this discrepancy is not known. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472274
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Improved potential energy surfaces for the interaction of H2 with Ar, Kr, and Xe (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 837-853 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A combined analysis of discrete infrared and microwave spectra, elastic and inelastic differential cross section measurements, and virial coefficient data has been used to determine improved potential energy surfaces for the H2–Ar, –Kr, and –Xe systems. Key improvements over previous surfaces for these species are an improved delineation of the diatom bond length dependence of the potential anisotropy, and the first experimental determination of a distinct P4(cos θ) anisotropy for an atom–diatom system. The effective anisotropy strength seen by bound state properties (such as transition frequencies) is found to increase from H2–Ar to H2–Kr to H2–Xe, although that seen by properties sensitive to the short-range potential (such as rotational predissociation and rotational inelasticity) decreases along this series. This reflects the lack of conformality of the various potentials; however, both these and analogous trends predicted for properties such as vibrational frequency shifts and vibrational inelasticity are readily understood in terms of the detailed properties of these surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452284
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    A reliable new potential energy surface for H2–Ar (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 2639-2653 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A reliable new three-dimensional potential energy surface is obtained for the H2–Ar system using an exchange-coulomb potential model with five parameters determined empirically from a least-squares fit to experimental data. This surface fully accounts for new high resolution IR data, virial coefficients, and vibrational transition pressure-shifting coefficients used in the analysis, and yields excellent predictions of elastic and inelastic scattering cross sections and hyperfine transition intensities not included in the analysis. Quantitative comparisons with the best previous empirical potential and a high quality fully ab initio potential are also presented. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472127
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    A "modified Lennard-Jones oscillator" model for diatom potential functions (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 3949-3957 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A flexible new analytical representation for the internuclear potential energy of a diatomic molecule is proposed and tested. The new model may be thought of as a generalization of the prototypical Lennard-Jones (2n,n) function, with the form V(R)=De[1−(Re/R)ne−β(z)z]2, where z=(R−Re)/(R+Re) is a dimensionless radial distance variable which approaches 1 as R→∞. This form explicitly incorporates the theoretically predicted attractive inverse-power asymptotic behavior V(R)=D−Cn/Rn associated with most potential energy curves. This "modified Lennard-Jones" (MLJ) function is tested against other flexible forms for the potential energy by performing nonlinear least-squares fits both to known numerical potential curves and to spectroscopic line positions. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480946
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Fourier transform spectroscopy of BaO: New ground-state constants from the A 1Σ+–X 1Σ+ chemiluminescence (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 3026-3033 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The A 1Σ+–X 1Σ+ emission spectrum of BaO excited in a Broida-type oven was revisited using a Fourier transform spectrometer. Chemiluminescence was observed from excited BaO molecules generated from the Ba+N2O reaction, and 82 vibrational bands of 138BaO were measured in the range 8900–21 000 cm−1 at a resolution of 0.04 cm−1. Vibrational levels were observed up to v″=20 of the ground state and up to v′=11 for the excited state. In addition, 72 bands from the minor isotopomers 137BaO, 136BaO, and 135BaO were detected with v″ up to 14 and v′ up to 4. Over 15 500 lines with J″ up to 119 were measured with a precision of about 0.005 cm−1, which shows that the Broida oven is an excellent source for high-resolution emission spectroscopy. Our main goal here is to obtain an optimum set of molecular constants for the ground electronic state. To avoid complications due to the well-known perturbations for vA′≥1 of the A 1Σ+ state, our unified combined-isotopomer analysis used a novel combination of a Dunham expansion description of the ground state with independent band-constants for data involving A-state level vA′=0, while fitting to an independent term value for each observed A-state vA′≥1 vibration–rotation level of each isotopomer. Significantly improved ground-state constants and A-state vA′=0 band constants are obtained, together with term values for some 1372 higher-v′ A-state levels. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1286977
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Direct potential fit analysis of the X 1Σg+ state of Rb2: Nothing else will do! (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 3067-3076 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: High resolution A-X emission data involving vibrational levels of the ground X 1Σg+ electronic state up to v″=113, spanning 99.8% of the potential well, have been acquired for three isotopomers of Rb2. While a good fit (σ¯f=1.03) to the 12 148 transition frequencies (with uncertainties ±0.001 cm−1) is obtained from an unconstrained combined-isotopomer Dunham-type analysis, it requires a large number (62) of expansion parameters, and the resulting empirical centrifugal distortion constants (CDCs) are unreliable for extrapolation to higher-J. Moreover, Dunham expansion fits using constrained theoretical values of the first six CDCs (up to Ov) fail to properly represent the data, as even higher-order CDCs are required. However, a direct fit of these data to an analytical "modified Lennard-Jones" potential energy function involving only 16 fitted parameters yields essentially the same quality of fit as did the unconstrained Dunham fit, and should be reliable for extrapolation to arbitrarily high J. This potential form incorporates the proper R−6 asymptotic behavior of the potential, and is constrained to have the theoretically predicted C6 dispersion coefficient. Although the dataset involves the three isotopomers 85,85Rb2, 85,87Rb2, and 87,87Rb2, none of the present analyses was able to determine any Born–Oppenheimer breakdown effects. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1286979
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...