Decay dynamics of H2O(1B1): full characterization of OH product state distribution

Desorption of hydroxyl radicals in the vacuum ultraviolet photolysis of amorphous solid water at 90 K

“…The translational energies of OH͑v =0͒ and OH͑v =1͒ from fresh ASW are mostly fitted with a temperature T trans = 1300Ϯ 300 K. This temperature ͑translational energy= 5.2Ϯ 1.2 kcal/ mol͒ is in accordance with ϳ1600 K that was reported in the gas phase photodissociation of water at 157 nm by Mikulecky et al 31 and the MD calculations ͑4.5-6.0 kcal/mol͒ by Andersson and co-workers. 18,19 A small contribution ͑5%-10%͒ of the fast ͑T trans = 7500 K͒ component would be due to the secondary photoprocess from the H 2 O 2 products on ASW since the ASW surface was not completely covered with fresh H 2 O vapor even with intermissive H 2 O deposition.…”

“…18,19 A small contribution ͑5%-10%͒ of the fast ͑T trans = 7500 K͒ component would be due to the secondary photoprocess from the H 2 O 2 products on ASW since the ASW surface was not completely covered with fresh H 2 O vapor even with intermissive H 2 O deposition. The rotational temperatures T rot ͑v =0͒ = 400 K and T rot ͑v =1͒ = 300 K are not thermally equilibrated with the ice film temperature of 90 K. Mikulecky et al 31 reported T rot ͑v =0͒ = 620 K and T rot ͑v =1͒ = 460 K for OH formed from the gas phase photodissociation of H 2 O. These results suggest that we observed nascent OH photofragments originated from the ASW surface.…”

State‐to‐state photodissociation dynamics of the water molecule

“…The absorption spectrum of the A band is broad and structureless, indicating a fast and direct bond breaking reaction on the single e A 1 A 00 PES. As a prototype of adiabatic dissociation process, this system has been extensively investigated by both experimental [26][27][28][29][30][31][32][33][34] and theoretical [35][36][37][38][39] studies and is considered as 'well-understood'. 10 The remaining questions include the OH population in its fine structures, for which only a simple Franck-Condon (FC) model exists.…”

H2O photodissociation dynamics based on potential energy surfaces from density functional calculations

“…In addition, the fit of Engel et al 21 of the excited state PES has been used in numerous dynamical studies of the photodissociation. 17,18,[21][22][23][24][25][26][27][28] With little if any exceptions, the ab initio calculations reproduce the experimental data on a quantitative level. 19 As a further test of the DFT treatment, we will also show results of wave packet calculations using the excited state DFT potential energy surface, comparing both directly with experiment and with wave packet results 22 of dynamics calculations performed on the CEPA surface.…”

“…21 From the DFT calculation, we find 0 : 1 : 2 ϭ1:0.96:0.69, and from the SM-CEPA calculation, we find 0 : 1 : 2 ϭ1:0.80:0.49. However, it should be pointed out that there is some controversy regarding the measurement of the OH vibrational state distribution: Mikulecky et al 17 have measured a ratio 0 : 1 ϭ1:0.56 for the same wavelength. Measurements have also been performed for a wavelength of 177.3 nm ͑6.99 eV͒.…”