Standoff Methods for the Detection of Threat Agents: A Review of Several Promising Laser-Based Techniques

Figure 2

A representative spectral snippet from the nitrobenzene spectrum in the 14-micron region. This trace was recorded utilizing a Pb-salt diode laser spectrometer and a FM modulated detection scheme. There are 17 clearly defined rotationally resolved nitrobenzene transitions FM modulated signal shown in the top panel. The lower traces are recorded simultaneously with signal channel and are used for frequency calibration purposes.