Demonstrated Wavelength Portability of Raman Reference Data for Explosives and Chemical Detection

Figure 2

Calibration scheme demonstrating how Stokes and anti-Stokes lines are used to calibrate the laser frequency such that the Stokes lines are at the same shift with the opposite sign of the anti-Stokes lines. The present data show Raman lines of potassium permanganate. Typically the values are ≤ 0.20 cm⁻¹ absolute value of each other. The excitation laser line is nominally at 9397.58 cm⁻¹ (air) absolute frequency, but has typical daily variations of ±0.50 cm⁻¹ or more.