ELSEVIER International Journal of Mass Spectrometry and Ion Processes 149/150 (1995) 267-278 Collision-induced dissociation of Nl(X3C-) with Ne, Ar, Kr, and Xe* Chris L. Haynes, W. Freysinger,’ P.B. Armentrout* Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA Received 10 April 1995; accepted 19 June 1995 Abstract A guided-ion beam mass spectrometer is used to examine the collision-induced dissociation of ground state N: (3x-) from thermal to 20 eV energy with Ne, Ar, Kr, and Xe. The product distribution observed in these systems varies substantially, a result that can be attributed to the large variation in the polarizabilities and ionization energies of the rare gases. The threshold for appearance of N+ in these systems is measured to be 3.74 f 0.08 eV and is equated with the N+-N2 bond energy. The adiabatic charge transfer reaction of N: with Xe allows a determination of the ionization energy of N3 as 11.10 f 0.04 eV, in good agreement with a literature value determined by photoelectron spectroscopy. This information allows the heats of formation of N3 and N: to be determined as 4.61 f 0.09 and 15.67 i 0.08 eV, respectively. This thermodynamic information is compared with other available values. We also measured the adiabatic bond energies Q,(N+-Ar) = 1.22 f 0.46 eV, &(Kr+-N) = 1.38 f 0.13 eV and D,,(Xe+-N) = 0.65 k 0.10 eV. Keywords: Collision-induced dissociation; Nitrogen; Rare gases 1. Introduction N3 and other radical species are of potential importance as pumping media in chemical lasers [l]. Basic molecular information, such as ionization energies (IEs) and bond dissocia- tion energies (BDEs), concerning this radical and its ion are needed to model accurately * In honor of Professor David Smith FRS on the occasion of his 60th birthday. * Corresponding author. ’ On leave from Institiit fiir Ionenphysik der Universitlt Innsbruck, TechnikerstraDe 25, Innsbruck, Austria. Present address: Universitlt HNO-Klinik, AnichstraDe 35, A-6020, Innsbruck. Austria. nitrogen discharge plasmas [2], fast chemical reactions involving the azide molecule [3], and in atmospheric studies [4,5]. Studies of such short-lived radical species are a challenge for experimentalists. Literature data on the heats of formation of N3 and Nt are collected in Table 1 and show a wide variation. Apart from an early theoretical investigation in the early seventies [6], quantum chemistry has only recently started to investigate N3, Nf, and related radical species [7-121. The aim of the present investigation is to determine directly IE(N3) and Q,(N+-N2), which then allows Do(N-N2) to be determined as well. With a few exceptions [ 13- 151, much of the previous 0168-l 176/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDI 0168-1176(95)04255-S