Rotational-resolved pulsed field ionization photoelectron study of NO+(X-1Sigma(+),v(+)=0-32) in the energy range of 9.24-16.80 eV

We have obtained rotationally resolved pulsed filed ionization photoelectro n (PFI-PE) spectra of NO in the energy range of 9.2-16.8 eV, covering ioniz ation transitions of NO+(X (1)Sigma(+),v(+)=0-32,J(+))<-- NO(X (2)Pi(3/2,1/ 2),v"=0,J"). The PFI-PE bands for NO+(X (1)Sigma(+),v(+)=6-32) obtained her e represent the first rotationally resolved spectroscopic data for these st ates. The simulation using the Buckingham-Orr-Sichel model provides accurat e molecular constants for NO+(X (1)Sigma(+),v(+)=0-32), including ionizatio n energies, vibrational constants (omega(e)(+)=2 382.997 +/- 0.122 cm(-1), omega(e)(+)chi(e)(+)=17.437 84 +/- 0.000 90 cm(-1), omega(e)(+)y(e)(+)=0.06 3 209 5 +/- 3.2x10(-6) cm(-1), and omega(e)(+)z(e)(+)=-0.001 400 0 +/- 7.2x 10(-8) cm(-1)), and rotational constants (B-e(+)=1.996 608 +/- 0.006 259 cm (-1), alpha(e)(+)=0.020 103 +/- 6.3x10(-5) cm(-1), and gamma(e)(+)=-(7.22 /- 2.26)x10(-6) cm(-1)). For v(+)=0-15, the rotational branches are Delta J =J(+)-J"=+/- 1/2, +/- 3/2, +/- 5/2, +/- 7/2, and +/- 9/2, which correspond to the formation of photoelectron angular momentum states l=0, 1, 2, and 3. The Delta J=+/- 1/2, +/- 3/2, +/- 5/2, +/- 7/2, +/- 9/2, and +/- 11/2 rota tional branches are observed in the spectra for v(+)=16-32, revealing the p roduction of continuum photoelectron states l=0, 1, 2, 3, and 4. The maximu m Delta J value and intensities for high Delta J rotational branches are fo und to generally increase as v(+) is increased in the range of 0-32. This o bservation is attributed to an increase in inelastic cross sections for col lisions between the outgoing photoelectron and the nonspherical molecular i on core as the bond distance for NO+ is increased. Thus, this observation c an be taken as strong support for the electron-molecular-ion-core scatterin g model for angular momentum and energy exchanges in the threshold photoion ization of NO. (C) 1999 American Institute of Physics. [S0021-9606(99)00930 -7].