Doppler Free Spectroscopy by Masked Imaging Vasiliy Goncharov

Doppler Free Spectroscopy by Masked Imaging Vasiliy Goncharov, Nuradhika Herath, Andres Arregui and Arthur G. Suits Department of Chemistry Wayne State University Detroit MI 48202

Doppler free spectroscopy • Elimination of one-photon or multi-photon Doppler broadening • Use only one laser beam • This technique involves masking the detector under the velocity map conditions

Ion Imaging • Developed in 1987, ion imaging allows the detection of single product quantum states with sufficient velocity resolutions • Variants Velocity mapping Slice imaging D. Chandler, P. Houston, J. chem. Phys, 87, 2, 1445 http: //ms. cc. sunysb. edu/~asuits/pages/research. html

Experiment W to unmasked full ion cloud signal For ≥ W/2 Ion count is multiplied by /(2 arcsin{W/2 }) For < W/2 nothing is done

Applications

CO from Acetone CH 3 COCH 3 + hv 2 CH 3 + CO B 1 +(v =0) X 1 +(v =0) REMPI spectra of CO 0. 6 cm-1 CO+ B 1 Ʃ+ X 1 Ʃ+ 1 cm-1

Hot CO from OCS B 1 +(v =0) X 1 +(v =0) REMPI spectrum of CO Constants Ref. Values (cm-1) Present work (cm-1) B 0 1. 948186 1. 948112(6) D 0. 106 6. 6355(12) 6. 6873(30) H 0. 1011 -2. 161(19) -1. 492(36) Rotational Analysis: E= 86916. 18+ (Bo’ -Bo”) J (J+1)-(Do’ -Do”) J 2 (J+1)2+(Ho’ Ho”) J 3 (J+1)3 V. Mc. Koy and coworkers, JCP, 116, 7, p. 2776, 2002

O atom O 3 + hv O 2 + O (3 P) 3 P 0 3 P 1 3 P 2 3 P 0 3 P 3 P H atom 1 S 1 2 2 P 2 P 3/2 2 P 1/2 2 S 1/2

Summary • • Use only one laser Eliminate one photon or multi photon Doppler broadening Applicable to ionization only Cannot use for LIF

Acknowledgment Funding: DOE-BES