An electron bombardment procedure for generating cation and neutral radicals in solid neon matrices at 4 K: ESR study of 14N2+ and 15N2+

Abstract

Articles you may be interested inSystematic theoretical studies of the interaction of 1,4-diazabicyclo [2.2.2]octane (DABCO) with rare gases ESR and a b i n i t i o theoretical studies of the cation radicals 1 4N+ 4 and 1 5N+ 4: The trapping of ion-neutral reaction products in neon matrices at 4 K A new generation technique for matrix isolated cations and neutrals involving the electron bombardment of the matrix sample during deposition is presented. Use of the method for the study of ion-neutral reactions and other types of matrix experiments is discussed. Results for the gas phase electron bombardment of (CH3),O are compared with electron bombardment of (CH 3 ),O conducted during neon deposition. The relative amounts of N and Nt radicals trapped in neon matrices have been measured as a function of electron energies. An ESR analysis of "Nt and "Nt generated by electron bombardment in neon matrices at 4 K yields: gUo = 2.0004 (2); A : • .("N) = 104.1(6) MHz and A i • .("N) = 146.1(6) MHz. The ESR results are used to estimate the extent of s-p hybridization of Nt and a comparison with theoretical calculations and several other 13 electron diatomic radicals is made.

Fine and Hyperfine Structure in14N+2: TheB2Σ+u–X2Σ+g(0, 0) Band

“…The present value of b F for vЉ ϭ 0 is 1.6% (1.2) different from the matrix-isolation value (17), reaffirming the typical small effect of a rare-gas matrix on the hyperfine interaction. The difference in the value of the dipolar hyperfine constant t for vЉ ϭ 0 and vЉ ϭ 1 is 17% (4.7 standard deviations).…”

The and states of N2+: hyperfine and nuclear quadrupole coupling constants, electric quadrupole moments, and electron-spin g-factors. A theoretical study

“…ðX ; 0Þ ¼ À2420 ppm (ppm ¼ 10 À6 ), in agreement with an ESR value of )2400 ppm [14]. Further, cðX ; vÞ changes little up to v ¼ 5, and the same is expected for Dg ?…”

“…A survey of the experimental literature shows that the observed magnetic hyperfine coupling constants (hfccÕs) are internally consistent (i.e., the resulting spindensity is close to one) for X but not for B. Scholl et al [11] found A iso ðX ; 0Þ ¼ 102:4 MHz and A dip ðX ; 0Þ ¼ 23:3 MHz; both constants increase slightly between v ¼ 0 and v ¼ 2 [12,13]. (Here, MðN ; nÞ represents property M for the nth vibrational level of state N.) An electron spin resonance (ESR) study [14] on 14 N þ 2 (X) could only report isotropic values since free rotation of N þ 2 in the matrix made its full characterization impossible (A iso ðX ; 0Þ ¼ 104:1 MHz and hgi iso ¼ 2:0004). As shown in the literature [11][12][13][14], these hfccÕs give a total s-contribution of about 10%, in line with a singly occupied MO (SOMO) of type 2r g ðp r -p r Þ.…”

“…(Here, MðN ; nÞ represents property M for the nth vibrational level of state N.) An electron spin resonance (ESR) study [14] on 14 N þ 2 (X) could only report isotropic values since free rotation of N þ 2 in the matrix made its full characterization impossible (A iso ðX ; 0Þ ¼ 104:1 MHz and hgi iso ¼ 2:0004). As shown in the literature [11][12][13][14], these hfccÕs give a total s-contribution of about 10%, in line with a singly occupied MO (SOMO) of type 2r g ðp r -p r Þ.…”

Photon-Stimulated Desorption

“…In a recent study of Nt ions in a neon matrix, a surface charge of 25 to 35 V was observed. 53 If we assume a surface potential of 10 V on a film 1000 A in thickness, then the surface-charge density must be about 10 11 charges (ions)/cm 2 • Molecular ions are easily dissociated by low-energy electron impact: For gas-phase Nt and at, the cross section for dissociation by low-energy-electron impact has been reported as about 2 x 10-16 cm 2 . 54 Combining these two numbers produces a predicted N+ yield of 2 x 10-5 ions per incident electron, compared with 8.5 x 10-7 ions per photon from Table 1.…”