Negative ENDOR Study of an X-Ray Irradiated Crystal of Rochelle Salt

The negative ENDOR technique was used to study a C-H radical (center #2) in an X-ray irradiated crystal of ferroelectic Rochelle salt. Within the 8-20 MHz frequency range, signals from at least 11 different types of protons were detected. It was shown that a group which is broken from a tartate molecule upon irradiation is trapped in the immediate vicinity of the damaged molecule. This result suggested that center #2 is an electrically charged paramagenetic species, rather than a simple radical as previously surmised.