An algorithm for the calculation of hyperfine structure and spectra of diatomic molecules based on the variational nuclear motion is presented. Hyperfine coupling terms considered are Fermi-contact, nuclear spin-electron spin dipole-dipole, nuclear spin-orbit, nuclear spin-rotation and nuclear electric quadrupole interactions. Initial hyperfine-unresolved wavefunctions are obtained for given set of potential energy curves and associated couplings by variation solution of the nuclear-motion Schrödinger equation. Fully hyperfine-resolved parity-conserved rovibronic Hamiltonian matrices for a given final angular momentum, $\bm{F}$, are constructed and then diagonalized to give hyperfine-resolved energies and wavefunctions.Electric transition dipole moment curves can then be used to generate a hyperfine-resolved line list by applying rigorous selection rules.The algorithm is implemented in \textsc{Duo}, which is a general program for calculating spectra of diatomic molecules. This approach is tested for NO and MgH,and the results are compared to experiment and shown to be consistent with those given the well-used effective Hamiltonian code PGOPHER.
Astrophysical molecular spectroscopy is an important method of searching for new physics through probing the variation of the proton-to-electron mass ratio, $μ$, with existing constraints limiting variation to a fractional change of less than 10$^{-17}$/year. To improve on this constraint and therefore provide better guidance to theories of new physics, new molecular probes will be useful. These probes must have spectral transitions that are observable astrophysically and have different sensitivities to variation in the proton-to-electron mass ratio. Here, we concisely detail how astrophysical…
The theory of rovibronic spectroscopy of light-dressed molecules is presented within the framework of quantum mechanically treated molecules interacting with classical light fields. Numerical applications are demonstrated for the homonuclear diatomic molecule Na$_2$, for which the general formulae can be simplified considerably and the physical processes leading to the light-dressed spectra can be understood straightforwardly. The physical origin of different peaks in the light-dressed spectrum of Na$_2$ is given and the light-dressed spectrum is investigated in terms of its dependence on the …
Accurate knowledge of the rovibronic near-infrared and visible spectra of vanadium monoxide (VO) is very important for studies of cool stellar and hot planetary atmospheres. Here, the required ab initio dipole moment and spin-orbit coupling curves for VO are produced. This data forms the basis of a new VO line list considering 13 different electronic states and containing over 277 million transitions. Open shell transition, metal diatomics are challenging species to model through ab initio quantum mechanics due to the large number of low-lying electronic states, significant spin-orbit coupling…
The relative intensity distribution in the rotationally resolved laser-induced fluorescence spectra belonging to the $E(4)^1Σ^+\to (a^3Σ^+_1,X^1Σ^+)$ band systems of the KCs molecule was analyzed. The experimental intensities in doublet $P$,$R$ progressions assigned to spin-allowed $E\to X$ and spin-forbidden $E\to a$ transitions up to their common ground dissociation limit were described in the framework of a coupled-channels (CC) deperturbation model applied for the interacting \Xstate\ and \astate\ states. The CC intensity simulation was based solely on fixed electronic structure parameters…
We report an ab initio study on the rovibronic spectroscopy of the closed-shell diatomic molecule phosphorous mononitride, PN. The study considers the nine lowest electronic states, $X\,{}^{1}Σ^{+}$, $A\,{}^{1}Π$, $C\,{}^{1}Σ^{-}$, $D\,{}^{1}Δ$, $E\,{}^{1}Σ^{-}$, $a\,{}^{3}Σ^{+}$, $b\,{}^{3}Π$, $d\,{}^{3}Δ$ and $e\,{}^{3}Σ^{-}$ using high level electronic structure theory and accurate nuclear motion calculations. The ab initio data cover 9 potential energy, 14 spin-orbit coupling, 7 electronic angular momentum coupling, 9 electric dipole moment and 8 transition dipole moment curves. The Duo nu…
The present work reports results of the semi-empirical determination of the spontaneous emission transition probabilities (Einstein coefficients) for Q-branch lines of Fulcher-$α$ band system and radiative lifetimes of upper electronic-vibro-rotational (rovibronic) levels for the most important isotopologues of diatomic hydrogen. They are based on an adiabatic theoretical model and all currently available experimental data on rovibronic energy levels, ratios of the line strengths and the lifetimes. Numerical data are presented in tabular format for vibrational quantum numbers v=0-7 (N is the q…
Astrophysical molecular spectroscopy is an important means of searching for new physics through probing the variation of the proton-to-electron mass ratio, $μ$. New molecular probes could provide tighter constraints on the variation of $μ$ and better direction for theories of new physics. Here we summarise our previous paper \citep{19SyMoCu.CN} for astronomers, highlighting the importance of accurate estimates of peak molecular abundance and temperature as well as spectral resolution and sensitivity of telescopes in different regions of the electromagnetic spectrum. Whilst none of the 11 astro…
Duo is a general, user-friendly program for computing rotational, rovibrational and rovibronic spectra of diatomic molecules. Duo solves the Schrödinger equation for the motion of the nuclei not only for the simple case of uncoupled, isolated electronic states (typical for the ground state of closed-shell diatomics) but also for the general case of an arbitrary number and type of couplings between electronic states (typical for open-shell diatomics and excited states). Possible couplings include spin-orbit, angular momenta, spin-rotational and spin-spin. Corrections due to non-adiabatic effect…
Rovibronic spectra of the field-dressed homonuclear diatomic Na2 molecule is in- vestigated to identify direct signatures of the light-induced conical intersection (LICI) on the spectrum. The theoretical framework formulated allows the computation of the (1) field-dressed rovibronic states induced by a medium intensity continuous-wave laser light and the (2) transition amplitudes between these field-dressed states with respect to an additional weak probe pulse. The field-dressed spectrum features ab- sorption peaks resembling the field-free spectrum as well as stimulated emission peaks corresp…
Constraints on new vector boson mediated electron-nucleus interactions from spectroscopy of polar diatomic molecules
Helmholtz Institut Mainz（亥姆霍兹研究所美因茨）；GSI Helmholtzzentrum für Schwerionenforschung GmbH（GSI重离子研究中心有限公司）；Institut für Physik, Johannes Gutenberg-Universität Mainz（美因茨约翰内斯·古腾堡大学物理研究所）；University of California, Berkeley（加州大学伯克利分校）
