IR induced photochemistry of glycolaldehyde in nitrogen matrix

The conformational equilibria and IR isomerisation processes of glycolaldehyde (HOCH2CHO) conformers have been studied at low temperature in nitrogen cryogenic matrix. The effects of selective IR irradiation, in the νOH and νCH domains, have been followed by FTIR spectroscopy. After deposition the main form is the most stable one, CC (Cis-Cis), which features an intramolecular hydrogen bond. Upon selective IR irradiation, this latter form is able to interconvert into two open forms, those called TT (Trans-Trans), and TG (Trans-Gauche). From TT and TG forms, no recovering (by tunneling, dark process, irradiation, annealing, etc.) of the initial state (i.e. CC regeneration) has been observed. However, a TT ⇌ TG thermal equilibrium is observed with a standard reaction enthalpy about 0.37 kJ mol−1.

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