Quantitative comparison of multiple-photon absorption in polyatomic molecules
A quantitative comparison of multiple-photon absorption for a number of polyatomic molecules has been performed. A basis for this comparison has been developed that takes into account the different experimental conditions and molecular parameters, and provides suitable normalization of the fluence and absorption parameters. The normalization, and consequently the generalized interaction process can be specified in terms of the spectroscopic absorption cross section of the molecule sigma/sub 0/(..nu..) and the effective fraction of molecules that interact with the radiation field <f>. The results of the study indicate that in terms of the normalized absorption variables, multiple-photon absorption is a general phenomena that is qualitatively the same for all molecules; quantitative differences can be related to differences in sigma/sub 0/ and <f>. The absorption of all polyatomic molecules can be described in terms of the number of photons absorbed per molecule eta(PHI) at a fluence PHI. The data indicate that in spectral regions where sigma/sub 0/(..nu..) greater than or equal to 0.1 sigma/sub 0/ (max), eta(PHI) can be represented by the function PHI/sup ..gamma../ where ..gamma.. = 1 for sigma/sub 0/PHI/<f> < 1 and ..gamma.. approx. = 2/3 for sigma PHI/<f> > 1. Quantitative values of <f> and the functional dependence of eta(PHI) on the experimental parameters such as gas pressure, optical bandwidth, and optical pulse duration are derived and shown to be in good agreement with experimental data for SF/sub 6/. These results are also compared with the anharmonic oscillator model for multiple-photon excitation of polyatomic molecules.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 6133919
- Report Number(s):
- CONF-790690-3; TRN: 79-019588
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
POLYATOMIC MOLECULES
PHOTON-MOLECULE COLLISIONS
ABSORPTION SPECTRA
EXCITATION
PRESSURE DEPENDENCE
PULSE TECHNIQUES
COLLISIONS
ENERGY-LEVEL TRANSITIONS
MOLECULE COLLISIONS
MOLECULES
PHOTON COLLISIONS
SPECTRA
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena