Vibrational and rotational population distributions of MgH(v’’=0 and 1) produced in the reaction of Mg(3s3p1

Abstract

The population distributions of the rotational quantum states of the @ascent MgH(u" =0 and 1) produced in the reaction of Mg(3s3p P& ) with H2 are bimoda1. With the use of the surprisal method, the two components are separated. The minor low-N component of the distribution in the u"=0 state is found to be larger than that in the v" = 1 state, whereas, the major high-E component of the distribution in the v"=0 state becomes roughly equivalent to that in the v"=1 state. The two parallel low-N and high-N processes are expected to correspond to two distinct types of reaction dynamics. One (minor) type produces MgH in lower rotational levels and preferentially v"=0, and the other (major) type produces MgH in higher rotational levels with comparable v" =0 and v" =1 populations. Possible dynamical models are discussed. PACS number(s): 82.30.b, 34.50.s, 35.20.i

Dynamical and stereodynamical studies of alkaline-earth atom–molecule reactions

“…The ratio of their peak heights is $1 : 2, which is consistent with the experimental findings [7,8,35,42]. Assuming the individual rotational intensity of MgH up to N ¼ 30, the corresponding vibrational populations for the v ¼ 1 and 0 levels yield a ratio of 0.52, which is within the range of the observation 0.7 AE 0.2 [7,8].…”

“…The Mg(3s 1 S 0 ) þ H 2 reaction is endoergic by 27666 cm À1 . Upon excitation at 285 nm, the Mg(3s3p 1 P 1 ) þ H 2 reaction becomes exoergic by 7340 cm À1 , leading to the MgH(v,N) product [6][7][8][34][35][36][37][38][39][40][41][42][43]. The rotational state distribution shows a bimodal feature with a major large-N component and a minor low-N component.…”

Spectroscopic Properties of MgH2, MgD2, and MgHD Calculated from a New ab Initio Potential Energy Surface

“…[1][2][3][4][5][6][7][8][9][10] The ground state reaction Mg-( 1 S 0 ) + H 2 (g) f MgH 2 is endoergic and is inhibited by a large barrier. [10][11][12] It is generally accepted that MgH 2 is an intermediate in the gas-phase reactions Mg( 1 S 0 or 1 P 1 ) + H 2 f MgH + H. [1][2][3][4][5][6][7][8][9][10] However, despite its detection by infrared spectroscopy in low-temperature rare-gas matrixes, 13,14 stable gaseous MgH 2 was not observed until the work of Shayesteh et al in 2003. 15 Their high-resolution Fourier transform infrared emission spectroscopy studies yielded band origins and rotational constants for four vibrational bands of MgH 2 and one of MgD 2 .…”

Reaction dynamics of Mg(4 1S, 3 1D2) with H2: Harpoon-type mechanism for highly excited states

“…By taking into account the Hönl-London factors and intensity corrections for the low-N components (Nр5), 8 the rotational populations of MgH(vϭ0 and 1) are plotted, each showing a bimodal rotational distribution. As compared to those obtained by Mg(3 1 P 1 ) and Mg(4 1 S 0 ), 13 the normalized rotational distributions, which are represented by P branch transitions, are similar to each other within the experimental error as shown in Fig.…”

“…For the case of the excited Mg(3 1 P 1 ) state, the related reaction pathways leading to the MgH(v,N) product have been thoroughly investigated. [1][2][3][4][5][6][7][8][9] The resultant rotational state distribution shows a bimodal feature with a major large N component and a minor low N component. Like the case of O( 1 D) with H 2 , the Mg(3 1 P 1 ) -H 2 reaction is dominated by an insertion process tracking along the attractive 1 B 2 ͑C 2v symmetry͒ or 1 AЈ ͑C s symmetry͒ curve.…”