Much interest has been shown in IR cells capable of maintaining one or more samples at constant temperature, constant water vapour or gas pressure, or under vacuum conditions (Farmer, 1974). This note describes a cell capable of maintaining a vacuum between 10-3 torr and 10-4 tort from room temperature to 1000°C whilst the spectrum is being recorded; such cells have been constructed previously but for less severe conditions.
The cell and associated vacuum system are shown schematically in Fig. 1. The vacuum in the cell body is produced by an Edwards rotary pump and a normal mercury diffusion pump. To obtain a vacuum of 10-3 to 10-4 torr, a liquid nitrogen trap and foreline trap are used. The trap is filled with activated alumina. The O-ring seals in the cell are made of Viton. The constant vacuum control is obtained with Pirani and Penning gauges.