Matrix-isolated perchloric acid

It is easy to mix a volatile compound with a large excess of matrix gas in a bulb and to deposit this mixture at low temperture. The advantage of the resulting infrared spectrum of a matrix-isolated species over corresponding spectra obtained in the gaseous or the solid state is demonstrated by the spectra of perchloric acid, HCIO4, shown in Fig. 4.4-2. 

Figure 4.4-2 Infrared spectra of perchloric acid, HCIO4 a) in the gas phase at 295 K, 2 mbar in a 20 cm cell equipped with silicon windows b) isolated in an argon matrix at 11 K, 0.7 mmol, molar ratio 1 500. c) as a solid film at 50 K after slow evaporation of the argon from the matrix-isolated sample b). Note the changes in the band positions, band shapes, and absorbances between b and c.

---