Adiabatic potential energy curves of Cl2 (right)15 important for dissociation in the first absorption band (left).53 At short wavelengths the C 1Π1u state (green) dominates with the state (blue) becoming more important as the wavelength increases.
Adiabatic correlation diagram linking the atomic Cl(2P J ) states (right) with the molecular states in Hunds case (c) and (a) (middle), and molecular orbitals (left). The numbers give the occupancy of the 5σ g 2π u 25 molecular orbitals. The five states believed to be important in the photodissociation are also labelled (A, C, B, 3, and 4). Adapted from Refs. 6,8,18,19.
Diagram of the excited potential energy curves believed to be important in the photodissociation of Cl2.
Top panel: |c jk, u (R)|2 parameters, where j corresponds to the C 1Π1u state. These quantities correspond to the relative contributions of the different diabatic states to C 1Π1u . When the internuclear separation R is low, the C 1Π1u state has an almost one-to-one correspondence with the C 1Π1u state, but at larger R considerable spin-orbit mixing of the diabatic states occurs. Bottom panel: R dependence of the adiabatic transition dipole moments for the bright states of Cl2 in the Franck–Condon region.
Top panel: Diabatic potentials for the electronically excited states used in the photodissociation dynamics calculation. The diabatic states are defined by neglecting the spin-orbit couplings. Bottom panel: R-dependence for the spin-orbit couplings to the C1Π u state.
Simulated values for the total absorption cross-section. Experimental data points from the NIST database53 provided for comparison.
Upper panel: Partial cross-sections for the full photodissociation calculation. Lower panel: Close-up of states correlating to the (Cl + Cl*) exit channel.
Graphs showing Φ mn = cos [ϕ m − ϕ n ], where ϕ m and ϕ n are the fragment channels m and n, as a function of photon energy. The top panel corresponds to phase differences between Ω = 1 states, and the bottom panel corresponds to interferences between Ω = 1 and Ω = 0 states. See text for details.
Wavepackets for the Ω = 1 adiabatic potentials, sampled at different points in time. The y-axis scales are normalized to the initial wavepacket in the C 1Π1u state.
Top panel: Branching ratio between ground and excited state Cl as a function of wavelength. Bottom panel: Calculated energy dependence of the β(E) parameter for fragments in the excited channel. The dashed lines in each panel were obtained using the R-dependent transition dipole moments, the continuous lines were with a constant transition dipole moments.32
Energy dependence of the polarization parameter of the Cl* fragment, for photodissociation to the (Cl + Cl*) channel. Experimental results, including error bars, from Ref. 8 are provided for comparison.
Top panel: Energy dependence of the polarization parameter for the 35Cl( 2 P 1/2) photofragments as obtained from the full QM dynamical calculations (red continuous line). Experimental results from Kim et al. 9 (open circles) are shown for comparison, along with the semi-classical results of Asano and Yabushita (green dotted line).14 Bottom panel: as for the top panel but showing the QM dynamical results for the 37Cl( 2 P 1/2) photofragments (continuous blue line). The fully quantum dynamics results from this work are compared with the semi-classical results of Asano and Yabushita (black dotted line).14,16 The experimental results (open green triangles) are taken from Alexander et al. 8 Note that in both panels the sign of the theoretical data have been inverted.
Top panel: Coherent polarization parameter for the Cl fragment in the (Cl + Cl*) channel. Middle and bottom panels: Orientation polarization parameters for the Cl atoms produced in the ground (Cl + Cl) channel.
Correspondence between the mixed Hund's case (a)/(c) labels employed here, and their Hund's case (c) equivalents.
Laboratory frame alignment parameters reported from previous studies by Brouard and co-workers,12 Rakitzis et al.,26 Bracker et al.,25 and Rakitzis and Kitsopoulos28 at 308, 320, and 355 nm, respectively, for the Cl photofragments in the ground state product channel, and from Samartzis et al. 27 and Rakitzis et al. 26 for the excited state product channel. Errors (1σ) in the final digit(s) are given in parenthesis where appropriate.
Molecular frame alignment parameters reported from previous studies by Brouard and co-workers,12 Rakitzis et al.,26 Bracker et al.,25 Rakitzis and Kitsopoulos,28 and Samartzis et al. 27 and data are shown for the Cl fragments in the ground state product channel (top) while data are shown for the excited state product channel (bottom). Errors (1σ) in the final digit(s) are given in parenthesis where appropriate.
Laboratory frame orientation parameters reported from previous studies by Kim et al. 9 and Alexander et al. 8 Note that the authors used the values of the spatial anisotropy, β, from the work of Samartzis et al. 27 to calculate their orientation moments. Errors (1σ) in the final digit(s) are given in parenthesis where appropriate.
Molecular frame orientation parameters reported from previous studies by Kim et al. 9 and Alexander et al. 8 Note that the authors used the values of the spatial anisotropy, β, from the work of Samaratzis et al. 27 to calculate their orientation moments. Errors (1σ) in the final digit(s) are given in parenthesis where appropriate.
Parameters used in the propagation algorithms.
Definitions of the molecular frame polarization parameters26,48 in terms of expressions for the dynamical functions, f K (q, q ′),10 and expressions for the laboratory frame polarization parameters of Picheyev et al. 46,51 The V K (J) are J-dependent normalization factors, defined elsewhere.35,58 Adapted from a more extensive table presented in Ref. 46. Note that V 2(J) = 2.795 for J = 1.5.
Table of polarization parameters for photodissociation to the (Cl + Cl) channel. Columns from left to right: polarization parameter being determined, wavelength of the experiment performed, results from experiment,8,12,26,28 results from the adiabatic calculation, results from the full calculation, limiting values of the polarization moment.
Table of polarization parameters for photodissociation to the (Cl + Cl*) channel, for the Cl* atoms. Experimental results of Alexander et al.,8 results of the adiabatic calculation, results of the full calculation, and the theoretical limiting values of the polarization moments are provided for comparison. Note that the for the sign of the results from the full calculation have been reversed.
Table of appropriate correction factors to convert the experimental polarization moments to their axial recoil values (their limiting values in the absence of parent molecule rotation). Note that the γ values are estimate on the basis of the observed deviations in β from the limiting value of −1. The s 2 factor has not been included because it is unaffected by parent molecule rotation, and so its correction factor in all instances would be 1.
Article metrics loading...
Full text loading...