Table 2.

A summary of the values of the O1–H1 and the Ow–Hw stretching vibrational modes of enol form for all compounds in both S₀ and S₁ states and their spectral shifts ($\Delta \upsilon$ in cm⁻¹).

Compound	Wavenumber (cm−1)
	O1–H1			Ow–Hw
	S0	S1	$\Delta \mathit{\upsilon }$	S0	S1	$\Delta \mathit{\upsilon }$
3HF	3544	3002	541
3HFW	3129	2599	530	3510	3074	436
Form I	3617	3250	367
Form II	3574	3330	244
Form I-W	2967	2575	392	3662	3499	163
Form II-W	3063	2577	486	3526	3111	415