Determination of k‘−J‘ Correlations of Reaction Products by Fluorescence-Imaging Techniques. 1. Linearly Polarized Excitation Scheme

Abstract

A one-photon excited fluorescence detection scheme that employs fluorescence-imaging techniques is proposed to determine k‘−J‘ correlations of reaction products. To extract information of k‘−J‘ correlations from the fluorescence intensities of image patterns, a density matrix formalism is utilized to analyze both the linearly polarized and the circularly polarized detection schemes of a one-photon excited fluorescence process, in which a linearly polarized excitation laser is employed. Explicit fluorescence intensity formulas are given for various detection schemes and transition sequences. For the detection scheme that probes linearly polarized fluorescence photons, state multipoles of the density matrix of reaction products along various scattering angles θ, that is, population ( ) and alignment parameters ( ), can be uniquely determined by 12 independent measurements of the intensities of fluorescence imagings as functions of probe angles and transition sequences. Experiments which measure circularly polarized fluorescence photons can provide information on orientation parameters ( ) in the present detection scheme. Contributions of the individual term in the intensity formulas to the fluorescence imagings have been assessed by numerical calculations. A pattern recognition of fluorescence images of photofragments with v−J correlations has also been established.

An investigation of polarized atomic photofragments using the ion imaging technique

“…A very recent treatment of fluorescence imaging by Chen et al [40] gives expressions in terms of density matrix multipoles. While this treatment has much in common with the method discussed in this thesis, it provides no description or interpretation of the recoil angle dependence of the angular momentum polarization.…”

Study of Photodissociation Dynamics Using Sub‐Doppler Fluorescence Imaging Method: Photodissociation of ICN at 308 nm

“…1 This method mod i fies the flu o res cence im ag ing tech niques which were first ap plied by Chen et al to in ves tigate photodissociation and re ac tion dy nam ics. [2][3][4][5][6][7][8] To ob tain better ve loc ity and an gu lar res o lu tions us ing con ven tional flu o res cence im ag ing tech niques, the re ac tion zone has to be con fined in a tiny vol ume, which can be achieved by cross ing a well-collimated mo lec u lar beam with an other well-collimated re agent beam or a fo cused la ser beam. The dras tic decrease in the num ber den sity of re ac tion prod ucts due to the ex pan sion fol low ing the event of bi mo lec u lar col li sions or photodissociation, un for tu nately, has lim ited the num ber of flu o res cence im ag ing ex per i ments.…”

Theory for determining alignment parameters of symmetric top molecule using (n+1) LIF

“…Bain and McCaffery 33 employed the tensor density matrix and state multipolar formalisms to study the anisotropy of both ground and excited molecular arrays. Chen et al [34][35][36] proposed a theoretical treatment used for determining the population, orientation, and alignment parameters of reaction products by fluorescence-imaging techniques. In many reactions, some of the reaction products are symmetric top molecules.…”