ESR Study of HĊO in Single Crystals of Formic Acid at 77°K

Formyl radicals, HĊO, are formed when crystals of formic acid which have been gamma irradiated at 77°K are warmed to 195°K. An ESR study of these radicals in single crystals of formic acid has been made at 77°K. The $g$ tensor (principal values 2.0037, 2.0023, 1.9948) and the hyperfine tensors for the proton (principal values 337, 346, 378 MHz) and for ¹³C (principal values 341, 438, 317 MHz) were determined. These tensors are discussed in relation to the structure of the formyl radical.