Manabendra Sarma

Role of Photolysis Frequency in Enhanced Selectivity and Yield for Controlled Bond Breaking in HOD

Quantum dynamical calculations on HOD subjected to different combinations of IR and UV pulses have been made to isolate field attributes which maximize selectivity and yield in the photodissociation of the desired O-H/O-D bond. Results from IR/UV pulse combinations which provide very high selectivity and/or yield are analyzed in detail by using population transfer, probability density flow, and flux variations to obtain microdynamic details favoring selectivity and yield. Results indicate that a 2727 cm (-1) 50 fs Gaussian IR pulse in conjunction with a 46,062 cm (-1) 50 fs Gaussian UV pulse with a time lag of approximately 90 fs between the IR and UV pulses gives 79.1% flux in the H-O + D channel and 6.6% flux in the H + O-D channel, whereas a 3706 cm (-1) 50 fs IR pulse in conjunction with a 51 090 cm (-1) UV pulse gives 9.2% flux in the H-O + D channel and 82.1% flux in the H + O-D channel. A 2727 cm (-1) 50 fs IR pulse in conjunction with a 40,062 cm (-1) 50 fs UV pulse provides the greatest selectivity among the sampled field profiles with a flux branching ratio of H-O + D/H + O-D approximately 487.8, and a 3706 cm (-1) 50 fs IR pulse in conjunction with a 45090 cm (-1) 50 fs UV pulse achieves a flux branching ratio of H + O-D/H-O + D approximately 1354.8.

Laser assisted control of selective bond dissociation in HOD–some mechanistic insights

Quantum dynamical calculations on HOD subjected to different combinations of IR and UV pulses have been made to isolate field attributes which maximise selectivity and yield in the photodissociation of the desired O–H/O–D bond. Results from IR+UV pulse combinations which provide very high selectivity and/or yield are analysed in detail using population transfer, probability density flow, and flux variations to obtain microdynamic details favouring selectivity and yield. The expectation values for stretch and momentum in O–H and O–D bonds of the H–O–D molecule subjected to UV pulses effecting selective cleavage of these bonds have been analysed to decipher the mechanistic basis of selective dissociation. Fully quantum dynamical calculations using both the ground and excited potential energy surfaces with different initial states and UV pulses reveal that prior stretch in a bond before transferring it to the repulsive first excited state ensures preferential dissociation of this bond. The sampling of large stretch values and a quick downhill motion in the channel corresponding to dissociation of the prestretched bond on the upper surface are seen to underlie this preferential dissociation. †Dedicated to Professor H.F. Schaefer III on his 65th birthday.

An Examination of the Expectation Value Profiles for Average Stretch and Momentum in O-H and O-D Bonds of the HOD Molecule To Determine Their Role in Selective Photodissociation

The expectation values for stretch and momentum in O-H and O-D bonds of the H-O-D molecule subjected to UV pulses effecting selective cleavage of these bonds have been analyzed to decipher the mechanistic basis of selective dissociation. Fully quantum dynamical calculations using both the ground and excited potential energy surfaces with different initial states and UV pulses reveal that prior stretch in a bond before transferring it to the repulsive first excited-state ensures preferential dissociation of this bond. The sampling of large stretch values and a quick downhill motion in the channel corresponding to dissociation of the prestretched bond on the upper surface are seen to underlie this preferential dissociation.

Vibrational excitation resulting from electron capture in LUMO of F2 and HCl – A treatment using the time-dependent wave packet approach#

AbstractVibrational excitation cross-sections

Low energy electrons induced damage to selected DNA fragments

\sigma_{\nu_f \leftarrow \nu_i } (E)

Low-Energy Electron-Induced Single Strand Breaks in 2′-Deoxycytidine-3′-monophosphate Using the Local Complex Potential Based Time-Dependent Wave Packet Approach

in resonant e-F2 and HCl scattering are calculated from transition matrix elements

Investigation of dissociative electron attachment to 2′-deoxycytidine-3′-monophosphate using DFT method and time dependent wave packet approach

T_{\nu_f \leftarrow \nu_i } (E)

Effect of quantum tunneling on single strand breaks in a modeled gas phase cytidine nucleotide induced by low energy electron: A theoretical approach

obtained using Fourier transform of the cross correlation function

The role of the shape resonance state in low energy electron induced single strand break in 2'-deoxycytidine-5'-monophosphate.

\left\langle {\phi_{\nu_f } \left( R \right)\vert \Psi_{\nu_i } \left( {R,t} \right)} \right\rangle

Low energy electron induced cytosine base release in 2′-deoxycytidine-3′-monophosphate via glycosidic bond cleavage: A time-dependent wavepacket study

where