Middle and near infrared (MIR/NIR) spectrometry has
been used to characterize series of samples of LGx family and GaPO4.
Since OH impurities influence the material properties, their spectroscopy is
investigated in detail. The [190–3200 nm] region is measured in
transmission. Furthermore, the study of spectra made at Nitrogen liquid
temperature is used to follow the modification in the signature of some
defects present in the lattice and induced by treatments as γ
irradiation or annealing. At least, we show that these “new” materials
contain less OH-groups than quartz crystal