By linear polarized IR-spectroscopy (IRLD) in nematic solution, conducting a set of experiments at different concentrations of the analyte in solution of nematic host, and using reducing-difference procedure for IRLD spectra processing.
You can pay attention to ref. 1, for example.
[Ref. 1]. Arnaudov M., Ivanova B., Todorov S., Zareva S. Reducing-difference infrared spectral analysis of cis- and trans-configurated lactams, Spectrochim. Acta 63A (2006) 491-500