Fig. 2: In situ EPR spectra.

a–c Spectra of hydrated Cu-zeolites measured at 25 °C (a) and −150 °C (b) and dehydrated Cu-zeolites measured at −150 °C (c). d Double integrated peak area ratios of dehydrated and hydrated samples measured at −150 °C.

a–c Spectra of hydrated Cu-zeolites measured at 25 °C (a) and −150 °C (b) and dehydrated Cu-zeolites measured at −150 °C (c). d Double integrated peak area ratios of dehydrated and hydrated samples measured at −150 °C.