Quantifying the temperature sensitivity of practical spectra using a new spectroscopic quantity: Frequency-dependent lower-state energy

As is well known, individual molecular spectroscopic transition can be characterized by a single, fixed parameter that describes the transition's temperature sensitivity. This parameter is commonly known as the lower-state energy. In practical spectra, spectral lineshapes cause the effective lower-state energy to vary continuously as a function of frequency, and blending of adjacent features causes the effective lower-state energy to vary with temperature as well. Accordingly, a frequency-dependent lower-state energy can be defined. This lower-state energy is easily computed from measured or simulated spectra and is valuable for detailed assessment of the temperature sensitivity of practical spectra.

Research highlights► A new frequency-dependent lower-state energy Eν″ is defined. ► Eν″ is easily calculated from measured or simulated absorption spectra. ► Eν″ is valuable for detailed understanding of the temperature sensitivity of practical spectra.