Molecule Types Asymmetric Tops Samples

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The B¹E" state of NH₂D and ND₂H

The work is described in A.K. Saha, G. Sarma, C-H Yang, S. van de Meerakker, D.H. Parker and C.M. Western, Phys. Chem. Chem. Phys., (2015), doi:10.1039/C5CP01299F and C. H. Yang, G. Sarma, A. K. Saha, D. H. Parker and C. M. Western, Phys. Chem. Chem. Phys., 15, 6390 (2013), doi:10.1039/c3cp00012e. It is 2+1 multiphoton ionization electronic spectrum, made slightly more complicated as both the upper and lower electronic state have two interacting vibrational or vibronic states. See also The Jahn-Teller effect in the B state of NH3 for the vibrational energy levels.

• In the ground state there are two tunnelling split states, here labelled v=0 and v=1, linked by a J_aJ_c type perturbation.
• In the B¹E" excited state there are two closely spaced states, here labelled A2 and B1, which correspond to the two components of an electronic state that is degenerate (E") in NH₃ and ND₃. The terms that mix them reflect the fact that the degeneracy is not completely broken on isotopic substitution - see doi:10.1039/C5CP01299F. The sample simulation for NH₂D shows an overall spectrum (top, black) and transitions two the two indivi dual states (middle, blue=A2 and bottom, red=B1). This is selected with the plot style button () given colours set for the individual states.
• There are two transition moments, from v=0 in the ground state to A2 and B1 in the excited state. As discussed in doi:10.1039/c3cp00012e interference between these two states has a significant effect on the intensities - try changing the sign of one of the Strength parameters.

Data Files

Both the .pgo files and the linelist files used as input to the published fits are given here. Note the use of a constrain statement to force the C values in the two upper states to be identical:

Constrain NH3.ND2H.B.B1.C := NH3.ND2H.B.A2.C