Threshold Alignment Reversal and Circularly Polarized Fluorescence in Rotationally Resolved H₂

Authors

Jack W. Maseberg, Fort Hays State UniversityFollow
Klaus Bartschat, Drake University, Des Moines, IowaFollow
Timothy J. Gay, University of Nebraska - LincolnFollow

Date of this Version

2013

Citation

PHYSICAL REVIEW LETTERS 111, 253201 (2013)

DOI: 10.1103/PhysRevLett.111.253201

Comments

Copyright (c) 2013 American Physical Society. Used by permission.

Abstract

Using H₂ and D₂ targets, we have measured the polarization of Fulcher-band fluorescence resulting from spin-polarized electron-impact excitation of vibrationally and rotationally resolved d ³Π_u→ a ³ ∑_g⁺ transitions for incident electron energies from 14.3 to 28.5 eV. Near threshold, the linear polarization P₁ descends from positive values through zero to negative values, indicating a dynamic production of M_N = 0 states. The circular polarization P₃ is measured to be nonzero, indicating the orientation of rotationally resolved molecular states. For Q-branch transitions, P₃ is consistent with theory based on Hund’s case (b) coupling. The R-branch P3 values do not agree with theory equally well, indicating the effect of ∑-symmetry perturbation of the parent d ³Π_u⁺ state.