Fig. 6: Raman shift of the H2 stretching vibration in different isostructural X2H2 compounds. | Nature Communications

Fig. 6: Raman shift of the H2 stretching vibration in different isostructural X2H2 compounds.

From: High pressure synthesis of phosphine from the elements and the discovery of the missing (PH3)2H2 tile

Fig. 6

Upper panel. Table reporting the Raman frequency (cm−1) of the H–H stretching vibration of H2 molecules in different isostructural X2H2 crystals (\({\nu }_{{H}_{2}}\)(X2H2) with X = CH419, PH3, H2S26, H2Se27, and HI57) and their frequency shift (Δν) with respect to bulk H2 (\({\nu }_{{H}_{2}}\)(H2)) in comparable pressure conditions. Ref. 19 directly provides the frequency shift value for CH4. Lower panel. The molecular structures of CH4, PH3, H2S, H2Se, and HI, drawn according to the VSEPR theory and fulfilling the octet rule for the electron outer shell, are shown to highlight the absence of lone pairs on C in CH4, comparing to the other hydride forming elements.

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