OPTICAL-ACTIVITY IN THE METASTABLE STATE OF NA2[FE(CN)5NO]BULLET-2H2O CRYSTALS

The Na2[Fe(CN)5NO].2H2O crystal is transformed into its metastable state when it is irradiated with blue or green laser light at low temperatures below 160K. This work describes newly found anomalous optical properties in the metastable state. Under the observation with white light illumination and crossed polarizers, a bright color is visible due to the incomplete extinction. The spectrum of this color has a rather narrow band-width of about 15nm. The wavelength of the maximum intensity, lambda(MAX), shifts with the wavelength of the irradiated laser light, but is not affected by the thickness of the sample. The incomplete extinction at a narrow range of wavelengths can be explained in terms of the optical activity and the accidental coincidence of two principal indices of refraction at lambda(MAX). This suggests that the optical activity arises in the metastable state.