Ab initio calculations of nuclear quadrupole coupling constants of low‐lying rovibrational levels in the X1Σ+ and a1Σ+ states of all isotopic species of LiH (original) (raw)
Related papers
Journal of Molecular Spectroscopy, 1990
The 'Li, 6Li, and 'H quadrupole coupling constants of rovibrational levels of 'Li 'H+, 6Li 'H +, 'Li'H+, and 6Li2Hf in their three lowest-lying *Z+ electronic states have been calculated from molecular wave functions which explicitly describe nuclear displacement. The electronic excitation is predicted to lead to a significant increase in the strength of the Li coupling. The deuteron and 6Li coupling is found to be weak in all the electronic states. The vibrational dependence of the nuclear quadrupole coupling constants is found to be quite significant for all the isotopomem studied. The rotational dependence is predicted to be unimportant. The main features of the quadrupole coupling data are compared with those for the isotopic species of LiH in their X'Z+ and A 'Z + electronic states. Special attention is paid to relative magnitudes of the Li and D quadrupole coupling constants in the 'Li2H ' and 'Li *H + isotopic variants and to their changes with electronic, vibrational, and rotational excitation. The information about the changes is used to outline an approach to interpretation of the hypertine structure of the spectra of these isotopic species. A qualitative difference among the X ?Z+, 2 'Z+, and 3 'Z + quadrupole hyperfine patterns of 6Li2H+ is predicted. 0 1990 Academic press, hc.
Chemical Physics, 1991
The "B, "B, and 2H quadrupole coupling constants of rovibrational levels in the X %+ and B' *X+ states of "B'H+, "B'H+, "B'H+, and "B'H+ are calculated from molecular wavefunctions which explicitly describe nuclear motion. Except for the boron coupling in the B' %+ state, the vibrational dependence of the nuclear quadrupole coupling constants is found to be significant for all the isotopic species studied. The rotational dependence of the *H nuclear coupling constants is predicted to be unimportant. The changes with rotational excitation of the boron coupling constants are significant only for higher vibrational levels in the ground electronic state. The "B and i"B coupling is found to be relatively very strong for all isotopic variants, the ZH coupling in 'OB*H+ and "B*H+ is, especially in the B' *Z+ state, rather weak. The quadrupole hyperline structure of l"B2H+ and **B'H+ is essentially determined by relatively very strong boron coupling, the energy levels being perturbed by the deuteron coupling. In the B' *X+ state the perturbing effect is found to be negligible, in the low-lying rovibrational levels of the ground electronic state the corresponding splitting is found to be quite sizable.
Chemical Physics, 1991
The "B, rOB, and *H quadrupole coupling constants of rovibrational levels of r*B'H, r"B2H, "B'H, and "'B'H in their ground electronic state have been calculated from molecular wavefunctions which explicitly describe nuclear displacement. The "B and 'OB coupling is predicted to be relatively very strong for all isotopic variants. The vibrational dependence of the B coupling is found to be rather insignificant and its rotational dependence is predicted to be quite unimportant. The deuteron coupling in "'BZH and "B2H is found to be weak, its strength is ptedicted to decrease with vibrational excitation. The change with rotational excitation is unimportant. The quadrupole hypertine patterns of "%*H and "B2H in the X 'Z+ state are dominated by relatively very strong B coupling and their basic features are predicted to be independent of the vibrational and rotational state considered.
An anomaly in the isotopomer shift of the hyperfine spectrum of LiI
The Journal of Chemical Physics, 2005
A high-precision examination of the hyperfine spectrum of 6 LiI in comparison with 7 LiI shows a shift in the iodine nuclear electric quadrupole moment that cannot be accounted for by a model in which the electric field gradient at the iodine site is assumed to depend only upon the internuclear distance between Li and I. The other hyperfine interactions are consistent between the two isotopomers, including the previously reported electric hexadecapole interaction of the iodine nucleus.
Evidence for a nuclear hexadecapole interaction in the hyperfine spectrum of LiI
The Journal of Chemical Physics, 1999
The molecular beam electric resonance technique has been used to examine the hyperfine spectrum of 7 LiI to determine the nuclear hexadecapole interaction of the iodine nucleus. The nuclear magnetic octupole interaction was also considered but found to be marginally significant. A total of 172 transitions in vibrational states 0-3 and rotational states 1-6 have been included in a fit to determine the iodine nuclear quadrupole, spin-rotation, and hexadecapole interactions, the lithium quadrupole and spin-rotation interactions, and the tensor and scalar parts of the spin-spin interaction. Vibration and rotation dependencies of these constants have been determined. The results include: eHhϭϪ0.0151(30), eQ I q I ϭϪ194351.212(17)Ϫ8279.521(46)(vϩ1/2) ϩ100.616(34)(vϩ1/2) 2 Ϫ0.3949(73)(vϩ1/2) 3 Ϫ6.41977(50)J(Jϩ1)ϩ0.10593(33)(vϩ1/2)J(J ϩ1), eQ Li q Li ϭ172.613(52)Ϫ3.26(14)(vϩ1/2)ϩ0.00145(87)J(Jϩ1), c I ϭ6.80260(32) ϩ0.00303(49)(vϩ1/2)Ϫ0.000118(13)J(Jϩ1), c Li ϭ0.75872(72)Ϫ0.0088(11)(vϩ1/2), c 3 ϭ0.62834(68)Ϫ0.0050(11)(vϩ1/2), c 4 ϭ0.06223(36)ϩ0.00041(26)(vϩ1/2), and e⍀ I I Ј ϭ0.000112 , all in kHz with one standard deviation uncertainties for the last 2 digits in ͑ ͒.
Theoretical study of emission spectra for the isotopic molecule Lithium Li1 6H hydride
A study of the emission spectra of isotopic of LiH molecule for electronic states X1Σ has been carried out. The energies of the vibration levels ν = 0, 1, …, 25 and the values of spectral lines R(J) and P(J) were calculated. A relationship between the spectral lines and the rotational quantum number J = 0, 1, …, 25 was established. It was found that value of R(J) increases with the increase of J, while the value of P(J) decreases with the decrease of J. The Fortrat parabola corresponding to R(J) and P(J) was determined. It was found that the spectral line R(J) increases when the value of m increases, while the value of the spectral line P(J) decreases.
Chemical Physics, 1993
The "B, "'B, and 'H quadrupole coupling constants of rovibrational levels of "B2H, "'B'H, and "B'H in their B 'X+ state were calculated from molecular wavefunctions which explicitly describe nuclear displacement. The electric field gradient as a function of the internuclear distance was computed by use of the multi-reference configuration interaction approach, the radial rovibrational wavefunctions were obtained by the Fourier grid Hamiltonian method. The double-minimum character of the potential is seen to markedly influence the rovibrational dependences of the boron and deuteron coupling constants. The quadrupole hyperfine structure of all vibrational levels of "B'H and 1°B2H isotopomer is essentially determined by the relatively strong boron coupling which is perturbed by the deuteron coupling.
Nuclear electric quadrupole moment of6Li
Physical Review A, 1998
The molecular beam electric resonance technique has been used to examine the hyperfine spectrum of 6 Li 19 F for the purpose of obtaining an improved value of the ratio of the electric quadrupole moments of the two lithium nuclei. A total of 29 transitions in vibrational states 0-2 and rotational states 1-4 have been included in a fit to determine the Li nuclear quadrupole interaction along with the magnetic spin-rotation and spin-spin interactions. The magnetic interactions are consistent with values calculated from the previously reported 7 Li 19 F values, but those have been refitted to take advantage of the new information from 6 Li 19 F. The electric quadrupole moment ratio of the two lithium isotopes determined from measurements on the two forms of LiF is Q(6 Li)/Q(7 Li)ϭ0.020 161Ϯ0.000 013 ͑one standard deviation estimate͒. ͓S1050-2947͑98͒08504-7͔
Journal of Physics B: Atomic, Molecular and Optical Physics, 2015
Calculations of the sensitivities of rotational and rovibrational transitions of isotopic lithium hydride in the electronic ground state to a variation of the proton-to-electron mass ratio constant are presented. A highly enhanced sensitivity coefficient is observed for the splitting of near resonant transitions arising from a cancellation between rotational intervals and frequency shifts associated respectively to the isotope effect, to the anharmonicity and to the rotation-vibration interaction. It ranges from 73 748.47(1) to-21 672(137) for the transitions with low to intermediate rotational quantum numbers in the lowest vibrational energy levels. The splittings of rotational transitions of 7 LiD in the vibrational level v = 0 and 6 LiD in the vibrational level v = 2 have a sensitivity coefficient of ~-3 for J up to 29 and that of 6 LiH R(0) and 7 LiH R(1) rovibrational transitions in the v = 0 → 1 band has a sensitivity coefficient of-585. The approach allowed comparison of frequency intervals between rotational lines with ammonia inversion lines detected in the microwave spectra of B0218+357 quasar to put constraints to a variation of the proton-to-electron mass ratio.
Journal of Molecular Spectroscopy, 2016
A very accurate dipole moment curve (DMC) for the ground X 1 Σ + electronic state of the 7 LiH molecule is reported. It is calculated with the use of all-particle explicitly correlated Gaussian functions with shifted centers. The DMC-the most accurate to our knowledge-and the corresponding highly accurate potential energy curve are used to calculate the transition energies, the transition dipole moments, and the Einstein coefficients for the rovibrational transitions with ∆J = −1 and ∆v ≤ 5. The importance of the non-adiabatic effects in determining these properties is evaluated using the model of a vibrational R-dependent effective reduced mass in the rovibrational calculations introduced earlier (Diniz et al., Chem. Phys. Lett. 633, 89 (2015)). The results of the present calculations are used to assess the quality of the two complete linelists of 7 LiH available in the literature.