Knowledge Bank

Chemical analysis of fire debris is often conducted to determine whether accelerants were employed. The GC and GC/MS methods used in these analyses do not always offer the chemical specificity that the forensic chemist would like, however. In an effort to demonstrate the potential application of the Fourier-transform microwave (FTMW) spectrometer as a chemically-specific forensic tool we have collected the pure rotational spectra of the major constituents of one possible accelerant, turpentine. The major constituents are $\alpha$-pinene and $\beta$-pinene, and their spectra have been recorded from 8 GHz to 20 GHz. The spectrum of $\beta$-pinene has been assigned, and the rotational constants $A=1901.8889\pm 0.00048MHz,B=1293.66095\pm 0.00026MHz$, and $C=1150.83126\pm 0.00010MHz$, as well as several distortion constants, have been extracted from the data. Stark data have also been collected, from which the dipole moment will be determined. The spectrum of $\alpha$-pinene is currently under analysis. Because the rotational spectra for $\alpha$-pinene and $\alpha$-pinene are distinct, the relative amounts of the two constituents in a sample could be determined, something that would be useful in deciding if the detected pinenes are of natural orgin or not.