A researcher detects an absorption line at a frequency of 3.0×1014Hz for a diatomic gas and wants to study the accompanying rotational fine structure using the same instrument by increasing its spectral resolution only (no change in wavelength range). Which spectroscopy technique should the researcher employ?
(a) Raman spectroscopy
(b) Ultraviolet–visible spectroscopy
(c) Infrared spectroscopy
(d) Microwave spectroscopy