Dissociation of High-Lying Electronic States of NO₂⁺ in the 15.5–20 eV Region

Abstract

We present a dissociative photoionization study of NO 2 in the 15.5−20 eV energy range using synchrotron radiationbased double imaging photoelectron photoion coincidence (i 2 PEPICO) spectroscopy. The high-lying electronic states of the NO 2 + cation, c

Ro-vibrational Distribution of NO+ Dissociated from NO2+ Ions in the a3B2 and b3A2 States: A Slow “Impulsive” Dissociation Example Revealed from Threshold Photoelectron–Photoion Coincidence Imaging

“…As shown in Figure , the TOF distribution of NO + is broadened to more than 400 ns (fwhm) due to a great deal of released kinetic energy in dissociation. All these evidence strongly suggest that there is a relatively deep potential well of a 3 B 2 along the N–O bond, which is consistent with the previous studies. , Moreover, the triangle-like TOF distribution of NO + in Figure is different from the reported anisotropic profiles in the Eland and Karlsson’s PEPICO experiment, but it is consistent with the recent imaging PEPICO measurements. , …”

“…5,19 Moreover, the triangle-like TOF distribution of NO + in Figure 2 is different from the reported anisotropic profiles in the Eland and Karlsson's PEPICO experiment, 13 but it is consistent with the recent imaging PEPICO measurements. 17,33 To our surprise, a very wide NO 2 + ion peak was still observed at the higher energies like a 3 B 2 (0,4,0) and b 3 A 2 (0,0,0) in Figure 2. Apparently, its TOF distribution such as the width and profile is entirely different from that from direct photoionization of NO 2 monomer (black trace in Figure 2).…”

“…13 Moreover, the recoil angle for NO + fragments was verified to be ∼50°relative to the initial C 2v symmetry axis in dissociative photoionization of NO 2 via the b 3 A 2 ionic state at 14.4 eV. 32 In recent imaging PEPICO studies, 17,33 the state-specific dissociative photoionization of NO 2 + below 20 eV was systematically studied for the a 3…”

“…Moreover, the recoil angle for NO + fragments was verified to be ∼50° relative to the initial C 2 v symmetry axis in dissociative photoionization of NO 2 via the b 3 A 2 ionic state at 14.4 eV . In recent imaging PEPICO studies, , the state-specific dissociative photoionization of NO 2 + below 20 eV was systematically studied for the a 3 B 2 , b 3 A 2 , A 1 A 2 , B 1 B 2 , c 3 B 1 , C 1 B 1 , d 3 A 1 , e 3 B 2 , and D 1 B 2 electronic states, respectively. The NO + fragment ions were observed at the ground vibrational level with a high rotational population, regardless of dissociation from NO 2 + (a 3 B 2 ,b 3 A 2 ) cations …”