Pollution monitor for nitric oxide: a laser device based on the Zeeman modulation of absorption

The Concentration of nitric oxide can be monitored by a new device in which the Zeeman effect is used to shift an absorption line of nitric oxide into coincidence with a laser line of carbon monoxide. The absorption is modulated by a small, oscillating magnetic field. This device is specific for nitric oxide and is not subject to interference from other gases.