RESONANCE FLUORESCENCE AS A PROBE TO ELUCIDATE MECHANISMS OF INTRA-MOLECULAR RELAXATION PROCESSES

被引:5
作者
CHEN, KM
YEUNG, ES
机构
[1] US DOE, AMES LAB, AMES, IA 50010 USA
[2] IOWA STATE UNIV SCI & TECHNOL, DEPT CHEM, AMES, IA 50011 USA
关键词
D O I
10.1063/1.438307
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Density matrix formalism is used to study resonance fluorescence processes of isolated gaseous molecules. The Wangsness-Bloch-Fano theory is applied to the irreversible intramolecular relaxation process. In the present treatment, it is assumed that the rotational angular momentum J is a constant of motion in the zeroth order approximation. Thus intramolecular interactions can be classified as tensor operators with respect to J. The fluorescence decay patterns depend on excitation bandwidths and monitoring conditions. Under narrow band excitation, the population (monopole), orientation (dipole), and alignment (quadrupole) of the excited state density matrix ρe can be prepared. For a sharply prepared angular momentum state under pulsed excitation, the population does not undergo radiationless decay and the resonance fluorescence intensity is a sum of three exponentials in general. For cw experiments, where lifetime limited linewidth or polarized fluorescence intensities are measured, the population can decay via an intramolecular relaxation channel providing the orientation component is initially prepared. Explicit J dependences of lifetimes are given for pulsed experiments. Under broad band excitation, quantum beats due to the coherence of ρe are derived from the Liouville equation. Most important of all, the population can decay under pulsed, broad-band excitation conditions. The scalar part of the nonadiabatic coupling becomes an additional contributor to the intramolecular relaxation process in this last case. © 1979 American Institute of Physics.
引用
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页码:4941 / 4950
页数:10
相关论文
共 26 条
[1]  
ABRAGAM A, 1961, PRINCIPLES NUCLEAR M
[2]   HIGH-RESOLUTION LIFETIME MEASUREMENTS OF ISOLATED VIBRONIC LEVELS IN NAPHTHALENE C10H8 [J].
BOESL, U ;
NEUSSER, HJ ;
SCHLAG, EW .
CHEMICAL PHYSICS LETTERS, 1975, 31 (01) :1-6
[3]   2-PHOTON EXCITED FLUORESCENCE SPECTROSCOPY [J].
CHEN, KM ;
YEUNG, ES .
JOURNAL OF CHEMICAL PHYSICS, 1979, 70 (03) :1312-1319
[4]  
Edmonds A. R., 1960, ANGULAR MOMENTUM QUA
[5]   COLLECTIVE MOTION IN THE NUCLEAR SHELL MODEL .1. CLASSIFICATION SCHEMES FOR STATES OF MIXED CONFIGURATIONS [J].
ELLIOTT, JP .
PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL AND PHYSICAL SCIENCES, 1958, 245 (1240) :128-145
[7]  
Freed K. F., 1976, Radiationless processes in molecules and condensed phases, P23
[8]  
FREED KF, 1972, TOP CURR CHEM, V31, P105
[9]   THEORY OF INFLUENCE OF ENVIRONMENT ON ANGULAR DISTRIBUTION OF NUCLEAR RADIATION [J].
GABRIEL, H .
PHYSICAL REVIEW, 1969, 181 (02) :506-&
[10]   MULTIPOLE RELAXATION TIMES OF A WEAKLY PERTURBED SPIN SYSTEM [J].
HAPPER, W .
PHYSICAL REVIEW B-SOLID STATE, 1970, 1 (05) :2203-+