A simplification of selective control using field optimized initial state with application to HI and IBr photodissociation

Abstract

An examination of the dependence of total flux from competing photodissociation channels on the photolysis field parameters and initial vibrational states for IBr and HI molecules reveals that, for a range of field attributes, considerable selectivity and yield may be obtained by using only the ground or the ground and the first excited vibrational states in the optimal linear combination constituting the field optimized initial state ͑FOIST͒. The new simplifications obviate the need for overtone excitations or multicolor photolysis fields making it easier to implement FOIST experimentally. Concrete specifications of field attributes for achieving selective control of IBr photodissociation products is provided.

Selective photodissociation of O–H and O–D bonds from ground vibrational state of HOD using simple UV pulses

“…We have shown elsewhere 41 that mixing of states may be replaced by mixing of colors, and we have therefore extended our approach to examine if two color lasers may be used for preferential dissociation of the O-D bond.…”

Selective control of HOD photodissociation using CW lasers

“…where the f is the diagonal matrix of the time integrated flux matrix F. The matrix elements of F in the ith channel are given by 38 Selectivity and yield can also be influenced by supplementing or substituting the mixing of vibrational states by mixing additional colours (frequencies) 38 to the resonant carrier frequency with a single or multicolour field E(t) = * cos i…”

“…The field attributes may be chosen for simplicity and chemical insight, and an optimal initial state is generated using FOIST. The FOIST scheme has been successfully applied for selective control of dissociation products in HI and IBr [36][37][38] and it is also our purpose in this paper to extend this approach to selective control of HOD photodissociation using CW lasers and to explore if we can supplant FOIST-based mixing of vibrational states with much easier mixing of laser colours.…”

“…[33][34][35] Furthermore, to exploit the dependence of photodissociation outcome on the initial vibrational state subjected to the photolysis pulse, we have been advocating the use of field optimized initial state (FOIST) scheme [36][37][38] which attempts to distribute the onus for selective control on both the field attributes and the molecular initial state subjected to the chosen photolysis pulse. The field attributes may be chosen for simplicity and chemical insight, and an optimal initial state is generated using FOIST.…”

Selective control of photodissociation in deutereted water molecule HOD

“…Furthermore, we have been advocating the use of field optimized initial state (FOIST) scheme (Gross et al, 1996;Vandana et al, 1998;Mishra, 1999a, b, 2000a) which attempts to distribute the onus for selective control on both the field attributes and the molecular initial state to be subjected to the chosen photolysis pulse both of which can be sampled separately and economically using simple time-dependent quantum mechanical (TDQM) techniques based on fast fourier transform (FFT) (Kosloff and Kosloff, 1983) and Lanczos propagation (Leforestier et al, 1991) to select a combination of field attributes which may be easier to realize experimentally. Earlier applications of the FOIST scheme to HI and IBr photodissociations have provided new insights and encouraging selectivity and yield (Vandana and Mishra, 2000b) and it is our purpose here to provide preliminary results from its application to selective cleaving of O-H and O-D bonds in the HOD molecule. Results from the first application of the FOIST scheme to HOD molecule are analyzed to try and garner features which may facilitate easier routes to enhanced selectivity and yield.…”