Terahertz time-domain and FTIR spectroscopy of tris-crown interaction

► Plasma-air based THz time-domain and FTIR techniques are compared. ► We investigate interaction between tris (hydroxymethyk) aminomethane and 18-crown-6. ► Vibrational spectra of tris pH3 and tris pH10 are calculated and compared with experimental data. ► Interaction of protonated and unprotonated tris with crown-ether is discussed.