Nonadiabatic fragmentation of excited molecular ions: An exploratory study for N2H+

F. A. Gianturco; G. Materzanini

doi:10.1007/s100530050215

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2023 Impact factor 1.5

Atomic, Molecular, Optical and Plasma Physics

Eur. Phys. J. D 4, 321-330 (1998)
https://doi.org/10.1007/s100530050215

Nonadiabatic fragmentation of excited molecular ions: An exploratory study for N₂H⁺

F. A. Gianturco^a and G. Materzanini

Department of Chemistry, University of Rome, Città Universitaria, 00185 Rome, Italy

Corresponding author: ^a fagiant@caspur.it

Received: 6 March 1998
Revised: 7 March 1998
Accepted: 23 June 1998
Published online: 15 December 1998

Abstract

The photodissociation of $\rm N_{2}H^{+}$ was studied in a one-dimensional approximation, with the aim of understanding the nonadiabatic features of the fragmentation dynamics. In the collinear arrangement of the system, the three lowest excited surfaces ( $^{1}\Sigma^{+}$ states) interact via two avoided crossings outside the Franck-Condon region, and they are strongly coupled radially by nonadiabatic terms. Electronic transition probabilities for the process ${\rm N_2}{\rm H^+}+h\nu\rightarrow(\rm N_2^{+})^{*} +{\rm H}$ , with $\rm N_2^{+}$ in one of the three lowest electronic states involved in the fragmentation, were calculated using the semiclassical multichannel S-matrix within the half-collision approach to photodissociation. The reliability of the semiclassical theory, for treating multichannel nonadiabatic processes was analyzed, and inelastic cross-sections for the three processes of electronically selected fragmentations were calculated. The structure found in the calculated absorption lineshapes reveals the marked influence of the nonadiabatic couplings between excited states in the fragmentation dynamics of this molecular ion.