High resolution FTS sunspot umbral spectra from NSO/Kitt Peak were used to detect rotational lines due to 11 electronic transitions of the molecule AlF, in the wavelength region 4400 -9000Å. The presence of lines due to bands C -A (0,0), (0,1), (0,2) and (1,2), D -A (0,0) and (0,1), F -A (0,0), G -A (0,0), and F -B (0,0) is confirmed. Further, the presence of lines due to C -A (1,0) and (1,1) transitions is treated as doubtful because of heavy blending in the region, by rotational lines of TiO. Among the identified lines, those which are well resolved were selected for measurement of equivalent widths. The measured values for the bands D -A (0,0) and F -A (0,0) were used to estimate the respective effective rotational temperatures to be 1240 ± 120 K and 2390 ± 400 K.

High-resolution Fourier Transform Spectrometer sunspot umbral spectra of the National Solar Observatory/National Optical Astronomy Observatory at Kitt Peak were used to detect rotational lines from 19 electronic transition bands of the molecules LaO, ScO and VO, in the wavenumber range of 11 775 to 20 600 cm −1 . The presence of lines from the following transitions is confirmed: 0) and B 2 Σ + -X 2 Σ + (0, 0) of ScO; and C 4 Σ − -X 4 Σ − (0, 1; 1, 0; 0, 2) and (2, 0) of VO. However, the presence of A 2 Π r3/2 -X 2 Σ + (0, 0) and C 2 Π r3/2 -A 2 r5/2 (0, 0; 1, 1) of LaO and C 4 Σ − -X 4 Σ − (0, 0) of VO are found to be doubtful because the lines are very weak, and detections are difficult owing to heavy blending by strong rotational lines of other molecules. Equivalent widths are measured for well-resolved lines and, thereby, the effective rotational temperatures are estimated for the systems for which the presence is confirmed.

For molecular identification in astrophysical sources, an astrophysicist needs some spectroscopic parameters such as dissociation energy, vibrational or rotational temperature of the source, band or line wavelengths, transition probability parameters, etc. The Franck-Condon(FC) factors are proportional to the transition probabilities. In this study, the FC factors and r-centroids for the vibronic (vibration-electronic) transitions C 1 + → X 1 + of aluminium hydride (AlH), b 3 (−) → a 3 , C 1 + → A 1 & C 1 → 1 of boron hydride (BH) have been evaluated and the results are presented in tables which include band origin/head wavelengths. The physical & astrophysical significances of our evaluated FC factors & r-centroids have been discussed and the possible presence of AlH in sunspot umbral spectra is also predicted.

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A high resolution spectrum of FTS sunspot umbra of NSO/Kitt Peak was used to conduct a search for the molecular absorption lines due to BeH, BeD and BeT isotopomers. Analysis led to estimates of identification of the molecular lines of bands A -X (0,0), (1,1) and (2,2) for BeH, A -X (0,0), (1,1), (2,2) and (3,3) for BeD and of A -X (0,0), (1,1) and (2,2) for BeT. Among the identified lines, those which are well resolved were selected for measurements to calculate equivalent widths. The values of effective rotational temperature T were estimated for bands A -X(1,1) and (2,2) of BeH, A -X(1,1) of BeD and A -X(2,2) of BeT to be 4228K, 4057K, 3941K and 3243K respectively.

High-resolution Fourier transform spectrometer sunspot umbral spectra obtained at the National Solar Observatory/Kitt Peak were used to identify molecular rotational lines arising from the infrared band systems of CrH and CrD molecules. Measurement of the equivalent width used the Gaussian-profile approximation method, which is suitable especially for faint lines. Equivalent widths are measured for an adequate number of best lines of the A -X (0, 0) band of CrH and the A -X (0, 0; 1, 0) bands of CrD and, thereby, the effective rotational temperatures are estimated.

The vibronic (vibration-electronic) transition probability parameters such as Franck-Condon (FC) factors and r-centroids of diatomic molecular species could be useful in the identification of molecular bands and in the estimation of relative abundance of the emitted species in astrophysical sources. In this study, they have been evaluated for the electronic transitions A2?r-X2?+, B2?r-X2?+ and C2?+ - X2?+ systems of BeH, A2?r - X2? and C2?+ - X2?+ system of BeD and A2?r - X2?+ system of BeT molecules using a suitable potential.

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