Abstract

The experimental study of the quantum properties of polyatomic molecules at high vibrational energy when classical chaos is present (quantum chaos) is discussed. Such a study requires the improvement of both experimental and analytical techniques. Methods by which stimulated-emission pumping spectroscopy and statistical Fourier-transform analysis of spectra can be successfully used to achieve this goal are emphasized. Stimulated-emission pumping and the statistical Fourier transform share the same concept of wave-packet preparation and evolution. This dynamical approach leads to interesting observations in molecular spectra. A numerical model of two coupled Morse oscillators provides information about the physical significance of the correlation hole observed in the Fourier transform of spectra of chaotic molecules. A relevant example in the experimental spectrum of CS₂ shows the destabilization of given periodic orbits in a regime of soft chaos. In such a case the destabilizing process starts with Fermi resonances. In CS₂ the chaos appears first in a portion of the degree of freedom (symmetric stretching and bending). In C₂H₂, in contrast, a new periodic orbit appears, corresponding to a new low-frequency mode that emerges from the chaotic bath of C₂H₂ and that could induce specific chemical reactions.

© 1990 Optical Society of America

Classical mechanical methods for extracting dynamics from stimulated-emission pumping spectra

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J. Opt. Soc. Am. B 7(9) 1935-1943 (1990)

Stimulated-emission pumping spectroscopy study of jet-cooled C₃: pure bending levels and bend–symmetric-stretch combination levels of X˜¹Σg+

F. J. Northrup and Trevor J. Sears
J. Opt. Soc. Am. B 7(9) 1924-1934 (1990)