In an extension of recent work [Y. Kim, K. Patton, J. Fleniken, and H. Meyer, Chem. Phys. Lett. 318, 522 (2000)], overtone pumping followed by resonantly enhanced multiphoton ionization (REMPI) detection is used to record spectra corresponding to excitation of the lowest five bend–stretch vibrational levels of the NO(X 2Π,v=2)–Ar complex. High-quality ab initio potential energy surfaces, coupled-electron-pair (CEPA) and coupled cluster single double triple [CCSD(T)], are used to predict the positions of these same five states, but in the NO(X 2Π,v=0)–Ar complex. The vibrational wave functions and basis set expansion coefficients, determined within the adiabatic bender model, are then used to simulate the observed spectrum for excitation of the NO(X 2Π, v=2)–Ar complex. The overall position and rotational substructure matches the experiment extremely well, particularly when the simulation is based on the presumably more accurate CCSD(T) potential energy surfaces.

Electronic states of the NO–Ne complex correlating with several low lying Rydberg states of the NO molecule are investigated using (2+1) resonance enhanced multiphoton ionization. The observed band systems for the states F 2Δ, E 2Σ, and C 2Π consist of at least two vibrational bands assigned to the stretching mode. For the H 2Π state five members of the stretch progression are observed. Binding energies range from 120 to 280 cm−1. The rotational structure of the observed bands is analyzed using a rigid rotor Hamiltonian. Jacobi bond angles between 50° and 85° are found for the vibrationally averaged structures. Spectra for the NO–X complexes (X=Ar, Ne) correlating with the vibrational levels C 2Π v′(NO)=0, 1, and 4 exhibit a constant red shift. The anomalous red shift found for the levels v′(NO)=2, 3 indicates a change in the degree of mixing with the state B 2Π upon complexation.

The rotationally resolved infrared spectrum of the NO–Ne complex associated with the first overtone transition in NO(X2Π) is measured in an IR-UV double resonance experiment. (2+1) resonance enhanced multiphoton ionization (REMPI) involving the Rydberg states E2Σ, F2Δ, and H2Σ,H′2Π is used to detect the infrared absorption. In the complex, the NO overtone transition is located at 3724.02 cm−1, i.e., it is blueshifted by 0.17 cm−1 from the transition in the monomer. Three other bands detected at frequencies 3727.85, 3732.56, and 3739.20 cm−1 are assigned to combination bands involving different intermolecular bend-stretch vibrations. The rotational structure of the observed bands is consistent with a near T-shaped complex. Details of the rotational structure resemble the spectrum of a symmetric top subject to weak electronic interactions causing a Stark-type and P-type doubling of the rotational levels.

No abstract

No abstract