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Probing Exciton Dynamics in the Frequency Domain Paul L. Raston and David T. Anderson Department of Chemistry, University of Wyoming, Laramie, WY 82071-3838 danderso@uwyo.edu WF14 Dynamics Probed by Spectroscopy, 5:44 pm Wed, June 20 Math Annex 160 62 nd International Symposium on Molecular Spectroscopy
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Brief Outline Excitons in solid parahydrogen Vibrons and rovibrons in rare gas atom and halogen atom doped solid parahydrogen Probing exciton dynamics in these systems Conclusions and future directions
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Vibrational excitation delocalized in solid pH 2 3.8 Å hexagonal close-packed Q 1 (0) V(H 2 -H 2 )=V(r 1,r 2,R, 1, 2, ) solidisolated 5 cm -1 vibron band VIBRON v,J= 0,0 1,0
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Rotational excitation delocalized in solid 3.8 Å hexagonal close-packed S o (0) V(H 2 -H 2 )=V(r 1,r 2,R, 1, 2, ) solidisolated 25 cm -1 roton band ROTON v,J= 0,0 0,2
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Vibron dynamics in chemically doped solid para-H 2 Br pH 2 3.8 Å hexagonal close-packed
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Deposit crystals from the gas-phase S. Tam and M. E. Fajardo, Rev. Sci. Instrumen. 70, 1926 (1999). room temperature dopant (e.g., Br 2 ) vacuum shroud optical substrate T = 2.4 K IR beam atmosphere vacuum cryostat cold tip catalytic converter Fe(OH) 3 UV beam 355 nm
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Vibrons in Rg atom doped solid para-H 2 para-H 2 Ne Ar Kr Xe Q 1 (0) V(Rg-H 2 )=V(r,R, ) solidisolated 5 cm -1 vibron band
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Vibrons in Br atom doped solid para-H 2 oH 2 Shifts are greater than for Xe Two peaks infer two different H 2 environments around Br( 2 P 3/2 ) V(Br---H 2 ) ab initio J. Klos, G. Chalasinski, and M. M. Szczesniak, JPC A 106, 7362 (2002).
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Rg atom perturbed S 1 (0) rovibron band S 1 (0) V(H 2 -H 2 )=V(r 1,r 2,R, 1, 2, ) solid v,J=0,0 v,J=1,2
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Br atom perturbed S 1 (0) rovibron band Xe Br
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pH 2 Study excitons using Br spin-orbit transition 1,2 2 P 3/2 2 P 1/2 h =3685.24 cm -1 e =0.96 s gas-phasesolid parahydrogen Br 1.M. Fushitani, T. Momose, T. Shida, CPL 356, 375 (2002). 2.P. L. Raston and D. T. Anderson, JCP 126, 021106 (2007).
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Br atom spin-orbit transition in solid para-H 2
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Br spin-orbit transition induced excitons
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Br spin-orbit + roton peak 25 cm -1
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Br spin-orbit + vibron peak
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Excitation energy above the barrier to reaction 7875 cm -1
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Br spin-orbit + rovibron peak
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Conclusions and future directions Inverse matrix isolation spectroscopy – use the matrix to tell you about the dopant Exciton line shapes reflect differences in atomic dopant species Exciton transitions build off Br spin-orbit transitions provide a new window into the exciton dynamics in a quantum solid Looking for theoretical collaborators to simulate exciton line shapes
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Publications and funding Paul L. Raston and David T. Anderson, “Infrared-active vibron bands associated with rare gas atom dopants isolated in solid parahydrogen,” Low Temp. Phys. (in press). Paul L. Raston and David T. Anderson, “Infrared spectroscopic studies of the rare gas atom perturbed S 1 (0) rovibron band of solid parahydrogen,” JMS (in press). This research sponsored in part by the Chemistry Division of the National Science Foundation (CHE 03-16268). Sharron C. (Cassie) Kettwich 1 st year graduate student Paul L. Raston, Ph.D. 2007
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