Fig. 4.

ESEEM detection of a ¹⁷O matrix line. Three-pulse ESEEM data from CcO incubated with 24% H₂¹⁷O for 10 msec (solid line) shows a peak at 2.2MHz, the Larmour frequency of matrix ¹⁷O at this field. Mn²⁺(H₂O)₆ in 22% ¹⁷O-enriched water (dotted line) also shows a peak at the same frequency. The large amount of noise in the CcO spectrum is caused by the small sample size and low concentration. Experimental conditions were as follows: temperature, 2 K; field strength, 3,420 G; microwave frequency, 8.852 GHz; power, 38 dBm; τ, 280 nsec; T, 40 nsec with 10-nsec increments.