AB initio calculation of the two-photon absorption cross section of the X 1 Σg+ → (E,F) 1 Σg+ IN H2

✍ Scribed by Winifred M. Huo; Richard L. Jaffe

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 905 KB
• Volume: 101
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(83)87514-9

✦ Synopsis

The two-photon absorption cross section of X IS+ g -(E.F) '$ of Hz has been computed ush~g near full CI wavefunctions. The convergence of the two-photon transition amplitude iskhieved by enforcb the variational wavefunctions to satisfy the off-diagonal S(O) and St--1) sum rules. The theoretical cross section agrees well with esperiment, I _ Introduction Two-photon spectroscopy 111 is a powerful tool in the study of excited states which cannot be populated by dipole-allowed transitions. One example is the X 12; + (E,F) 12: transition in Ha_ Kiigler and Rhodes [a] and Kligler et al. f3] used two-photon absorption and subsequent fluorescence to probe the collisional and radiative properties of the upper state. They also determined the two-photon absorption cross section [2] in the range of transition energies 103350-103681 cm-l. Their data showed that the dominant electronic relaxation channel for the (E,F) state is through inelastic scattering to the C III, state, whereas, the B '22: state plays the dominant role in its radiative quenching. They also conjectured that the B state is the dominant intermediate state in the two-photon excitation process, Recently, this transition was used by Mariner0 et al, [4,5] as an intermediate step in a quantum-state-specific detection of Hz by three-photon ionization, In view of the fundamental interest in multiphoton transitions and their importance as photodiagnostic probes in combustion and fluid-dynamics research, we have been engaged in a systematic study to devise reliable methods for the calculation of multiphoton transition probabilities. We demonstrated [6--81 the power of the perturbation approach in practical calculations * NRC-NASA Senior Research Assocjate (1979-1981).