Gas Sample Preparation

A gas sample is created by allowing the sample to expand into an evacuated cylindrical cell which has special windows than will not absorb the infrared light. The length of the cell can be anywhere from a couple of centimeters to over 10 meters. This cell will be placed in the beam path much like the solid or liquid sample with the exception that gas cell has two windows that the infrared light beam needs to pass through. Because the thermodynamics of the gas are such that it is very spread out the beam is bounced off the inside of the cell so that it will pass through the sample more to get more sample absorbtion.