共振电离谱学会议概述

第8届国际共振电离谱学及其应用会议(Eighth International Symposium on ResonanceIonization Spectroscopy and Its Applications)于1996年6月30日至7月5日在美国宾夕法尼亚州立大学召开。本届会议由田纳西大学共振电离谱学研究所和宾州州立大学联合主办。约100位科研工作者来自近30个国家,在会上发表论文109篇。其中我国清华大学2人,大连化物所、吉林大学各1名,在会上发表特邀报告1篇,口头报告2篇,展贴报告5篇。笔者的特邀报告"原子双里德堡态的自电离过程",引起了与会代表的关注。共振电离谱学是70年代发展起来的新兴研究领域,其主要特点是利用激光的高分辨率、高选择性,配合其他手段,实现高灵敏测量,以期在科学技术的各个领域中获得应用。

Femtosecond Stimulated Raman Line Shapes:Dependence on Resonance Conditions of Pump and Probe Pulses

Resonance enhancement has been increasingly employed in the emergent felntosecond stimu- lated Raman spectroscopy （FSRS） to selectively monitor molecular structure and dynamics with improved spectral and temporal resolutions and signal-to-noise ratios. Such joint eflforts by the technique- and application-oriented scientists and engineers have laid the foundation for exploiting the tunable FSRS methodology to investigate a great variety of photosensitive systems and elucidate the underlying functional mechanisms on molecular time scales. Dur- ing spectral analysis, peak line shapes remain a major concern with an intricate dependence on resonance conditions. Here, we present a comprehensive study of line shapes by tuning the Rarnan pump wavelength from red to blue side of the ground-state absorption band of the fluorescent dye rhodarnine 6G in solution. Distinct line shape patterns in Stokes and anti-Stokes FSRS as well as from the low to high-frequency modes highlight the competition between multiple third-order and higher-order nonlinear pathways, governed by difl^rent res- onance conditions achieved by Raman pump and probe pulses. In particular, the resonance condition of probe wavelength is revealed to play an important role in generating circular line shape changes through oppositely phased dispersion via hot luminescence （HL） pathways. Meanwhile, on-resonance conditions of the Rarnan pump could promote excited-state vibrational modes which are broadened and red-shifted from the coincident ground-state vibrational modes, posing challenges for spectral analysis. Certain strategies in tuning the Raman pump and probe to characteristic regions across an electronic transition band are discussed to improve the FSRS usability and versatility as a powerful structural dynamics toolset to advance chemical, physical, materials, and biological sciences.