MERGING OF THE SPLINE-POINTWISE AND MORSE/LONG-RANGE POTENTIAL FUNCTION FORMS FOR DIRECT-POTENTIAL-FIT DATA ANALYSES

Author Institution: Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada; Department of Physics, Sofia University, 5 James Bourcheier blvd, 1164 Sofia, BulgariaIn recent years it has become increasingly common to analyze diatomic molecule spectroscopic data by using fully quantum mechanical direct potential fits (DPFs) to determine the potential energy function(s) of the state(s) in question. However, the efficacy of this approach is strongly dependent on the quality of the analytic model used for the potential function. The two best models introduced to date are the `Morse/Long-Range' (MLR) function, 663 (2007); R.J. Le Roy {\em et al.}, {\em J.\ Chem.\ Phys.}\ {\bf 131} 204309 (2009).} which provides particularly compact, accurate and flexible functions which explicitly incorporate correct long-range and sensible short-range behaviour, and the `Spline Point-wise Potential' (SPP) form which is particularly successful for treating states with irregularly shaped potentials with a double-minimum or a 'shelf'.\ {\bf 128}, 622 (2000); {\em ibid, J.\ Mol. Spectrosc.}\ {\bf 203}, 264 (2000).} The present work shows that a merging of these two forms effected by representing the exponent coefficient function of the MLR model by a spline passing through a compact mesh of values yields most of the advantages of both approaches. Preliminary illustrative applications to the ground states of Ca$_2$ and NaRb will be presented

The X1Σ+^1\Sigma^+ and a3Σ+^3\Sigma^+ states of LiCs studied by Fourier-transform spectroscopy

We present the first high-resolution spectroscopic study of LiCs. LiCs is formed in a heat pipe oven and studied via laser-induced fluorescence Fourier-transform spectroscopy. By exciting molecules through the X$^1\Sigma^+$-B$^1\Pi$ and X$^1\Sigma^+$-D$^1\Pi$ transitions vibrational levels of the X$^1\Sigma^+$ ground state have been observed up to 3cm^{-1} below the dissociation limit enabling an accurate construction of the potential. Furthermore, rovibrational levels in the a$^3\Sigma^+$ triplet ground state have been observed because the excited states obtain sufficient triplet character at the corresponding excited atomic asymptote. With the help of coupled channels calculations accurate singlet and triplet ground state potentials were derived reaching the atomic ground state asymptote and allowing first predictions of cold collision properties of Li + Cs pairs.Comment: 10 pages, 5 figures. Submitted for publicatio

The Ground Electronic State of KCs Studied by Fourier Transform

Rakstā atspoguļoti pirmie KCs molekulas lāzera inducētas fluorescences (LIF) spektru analīzes rezultāti, kas iegūti ar ļoti augstu precizitāti, un veikta tieša potenciāla konstrukcija X 1Sigma+ pamatstāvoklim plašā starpkodolu attālumu diapazonā. KCs molekulas tika iegūtas, sildot K un Cs metālu maisījumu siltuma caurules tipa krāsnī pie temperatūras ap 270oC. KCs fluorescence tika ierosināta ar dažādiem lāzeru ierosmes avotiem: 454.5, 457.9, 465.8, un 472.7 nm Ar+ lāzera līnijām, krāsvielu lāzeri ar krāsvielu Rhodamine 6G (ierosme ap 16 870 cm−1), kā arī ar 850 un 980 nm diožu lāzeriem (atbilstošais frekvences skanēšanas diapazons attiecīgi 11 500– 11 900 un 10 200–10 450 cm−1). LIF uz pamatstāvokli tika reģistrēta ar Bruker IFS-125HR Furjē transformāciju spektrometru, kura spektrālā izšķiršana ir 0.03 cm−1. Īpaši jāatzīmē, ka, izmantojot 850 nm lāzera diodi, bija iespējams novērot LIF progresijas uz ļoti augstiem pamatstāvokļa svārstību līmeņiem tuvu disociācijas robežai. Pašreiz iegūtais datu lauks ietver 7226 termu vērtības X 1Sigma pamatstāvoklim un pārklāj diapazonu v′′=0 līdz 97, kur J′′ mainās no 12 līdz 209. Lai konstruētu pamatstāvokļa potenciālās enerģijas līkni, izmantojot apgriezto perturbāciju tuvinājuma procedūru, tika izmantotas vairāk nekā 10 000 fluorescences līnijas. Pašreiz iegūtā empīriskā potenciāla līkne turpinās līdz 12.6 Å un ietver vairāk nekā 99% no potenciālās bedres dziļuma, potenciāls apraksta lielāko daļu spektrāllīniju ar precizitāti ap 0.003 cm−1 un dod X 1Sigma+ pamatstāvokļa disociācijas enerģijas vērtību 4069.31.5 cm−1. Ir parādīti arī pirmā KCs molekulas tripleta pamatstāvokļa a 3Sigma+ novērojumi, kā arī iegūtas dažas galvenās molekulārās konstantes