A computer assisted procedure of assignments of vibration–rotation bands of asymmetric and symmetric top molecules

Advanced graphical software for assignments of transitions in rovibrational spectra

“…The development of experimental techniques, which produce large amounts of spectroscopic data and, on the other hand, a boom of computing power of personal computers with programming environments that enable creation of interactive application programs lead to development of various interactive programs, which facilitate the tedious procedures of assigning rotational and rovibrational molecular spectra [1][2][3][4][5][6][7]. Most of these programs are based on the original idea of the Loomis-Wood algorithm [8], which makes use of periodically recurring patterns of lines in the spectrum and organizes them is such a way that this periodicity is translated into emerging, visually recognizable continuous patterns in the so-called Loomis-Wood diagrams.…”

“…The latter approach is used in programs described in Refs. [3,5,6], where the first is designed for analyzing rovibrational spectra and includes also interactive combination difference (CD) checking. It can in principle work with any file of energies, but supplying it with levels from external calculations is done in a rather complicated way.…”

“…The CD approach has been used in the two mentioned programs [2,3], but each of them suffered from some inconveniences. The INFIA program [2] provides a very good graphical user interface, but its use is restricted to linear molecules and with certain limitations to symmetric top molecules.…”

“…The INFIA program [2] provides a very good graphical user interface, but its use is restricted to linear molecules and with certain limitations to symmetric top molecules. The other program with implemented CD checking [3] is general for any symmetric/asymmetric top molecule, but has only a semi-graphical representation of the LoomisWood diagrams. It displays only small sections of the infrared spectrum and does not provide facilities for displaying the whole spectrum.…”

“…[3], having both the lower and upper levels of the spectral branches represented by a table of energies with full sets of quantum numbers. These energies are not calculated on an approximate level, but can be imported from any external general fitting program through reading files generated by such programs.…”