Fine structure of the metastable a3Σu+ state of the helium molecule

Abstract

Lifetimes of fine structure levels of metastable H2 in the c 3Π u state J. Chem. Phys. 70, 4376 (1979); 10.1063/1.438010 Fine structure of the metastable a 3Σ u + state of the helium molecule. Further results J. Chem. Phys. 69, 98 (1978); 10.1063/1.436350 Some Excited States of the Helium Molecule. I. The Lowest 1Σ u + and 3Σ g + States and the First Excited 1Σ g + StatesWe have measured the spin-spin, electronic fine structure of the a 3~~ metastable state of He, by means of a molecular beam, magnetic resonance apparatus, with the flowing afterglow of a pulsed, helium discharge as the source. The zero field separations in the N = I and N = 3 rotational levels, probably in the v=O vibrational state, are (in MHz) N=I: J=0#J=1:2199.968 ±0.01, J = I #J = 2: 873.668 ±0.007; N= 3: J= 2#J~ 3: 1323.911±0.006, J=3#J=4: 964.992±0.006, where the errors quoted· are three standard deviations of the mean. From these measurements and from a separate determination of the level order, the interaction constants for these states are the following (in MHz): spin-spin: A.:-\098.773 ±0.OO5(N = I), -1096.803±0.004(N =3), spin-rotation: r: -2.421±0.OO3(N = I), -2.414±0.OOI(N =3), where the errors are 3u. Spin-spin interactions in moleculesMolecules in 3Z; states are of interest, because the first order fs is caused by magnetic, spin-spin interac-

Precision measurement of the rotational energy-level structure of the three-electron molecule He2+

“…2. Three Gaussian functions of full width at half maximum of 180 MHz, separated by the known fine-structure intervals [49][50][51][52][53] and with relative intensities weighted by the 2J + 1 degeneracy factors, were used to convert each observed triplet into its "fine-structure-free" center of gravity. All transition wavenumbers reported in this article correspond to such centers of gravity.…”

Determination of the Spin-Rotation Fine Structure of He2+

“…The spin-spin and spin-rotation interaction split each rotational level into three components with J = N , N ± 1. The characteristic spacing of the resulting fine structure of He * 2 has been measured for several rovibrational levels [31][32][33][34][35] and is dominated by the spin-spin interaction, which is two orders of magnitude stronger than the spin-rotation interaction [35]. The level structure of the X + 2 Σ + u (v + = 0) state of He 2 + is also best described using Hund's case (b).…”

“…All values are given in MHz. the fine-structure splittings of the metastable state are precisely known [31][32][33][34][35]44], the fine structure of the Rydberg states can be reconstructed in a straightforward manner, as illustrated in Fig. 4.…”

The absorption spectrum of the (1,0), (3,1) and (4,2) bands in the c3Σg+–a3Σu+ system of He2 eximer

“…Another fine structural study of the c 3 R g + -a 3 R u + system was carried out by Bjerre et al [12][13][14] using laser-radio double-resonance spectroscopy in 1990s. Focsa et al [15] reinvestigated the (0, 0), (1, 1), (2, 2), (1, 0) and (2, 1) bands in the c 3 R g + -a 3 R u + system by Fourier transform spectroscopy in 1998, and they performed a global fitting in combination with the data of Vierima et al [10,11] and Bjerre et al [13,14] to obtain precise molecular constants of the t = 0, 1 and 2 levels for both the c 3 R g + and a 3 R u + states. Recently, Vrinceanu and Sadeghpour [16] studied the low-temperature radiative transitions of the c 3 R g + -a 3 R u + system using molecular dimmer potentials method, and they gave the rovibrational frequency and the radiative transition squared dipole matrix elements.…”

“…In 1965, Ginter [9] studied the emission spectra in the c 3 R g + -a 3 R u + system using grating measurements, and nine bands (i.e., (0, 0), (1, 0), (2, 0), (1, 1), (2, 1), (3,1), (2,2), (3,2) and (4, 2) bands) were studied, which resulted in a set of molecular constants. In the late 1970s, Vierima and his coworkers [10,11] investigated the fine structure of spin-spin and spin-rotation interactions of the a 3 R u + state by employing highly precise magnetic resonance radio-frequency spectroscopy, and thus, the fine structural parameters for the N = 1 and 3 rotational levels of the t = 0 level were obtained. Another fine structural study of the c 3 R g + -a 3 R u + system was carried out by Bjerre et al [12][13][14] using laser-radio double-resonance spectroscopy in 1990s.…”