Theoretical study of electronic states of N_2~(2+) in an intense radiation field

摘要

The Floquet states of N_2~(2+) created by the interactions of the six lowest singlet (1 ~1SIGMA_g~+,1 ~1DELTA_g,2 ~1SIGMA_g~+,1 ~1PI_u,1 ~1PI_g,and 1 ~1SIGMA_u~-) states of the dication with intense (0.4 X 10~(13) W/cm~2) radiation have been studied using the recently developed multireference configuration interaction method with single and double excitations (MRClSD)-based approach.The adiabatic Floquet state coinciding near its minimum with the initial X ~1SIGAM_g~+ground state and asymptotically correlating with A ~1PI_u (m=-l),i.e.,with one less photon in the dressed state,is expected to be metastable,as is the ground state in the absence of a field,but to support up to the upsilon_(max)=12 quasibound vibrational level in comparison with upsilon_(max)=11 in the parent field-free X ~1SIGMA_g~+ground state.The tunneling lifetimes of the highest vibrational levels in this adiabatic Floquet state are predicted to be several orders longer than those in the parent field-free state.Analysis of the complete basis set limit extrapolated MRCISD potential energy curve of the field-free X ~1SIGMA_g~+state of N_2~(2+) calculated in the present work (R_e=1.130 A,omega_e=2011 cm~(-1),omega_ex_e=26.1 cm~(-4)) is in good agreement with spectroscopic experimental data.Calculations on the field-free A ~1PI_u state (T_e=l2 106 cm~(-1),R_e=1.252 A,omega_e=1438 cm~(-1),omega_ex_e=23.5 cm~(-1)) generally support earlier theoretical work and do not support reported experimental values.