Photoluminescence spectroscopy of 2-nitrotoluene and its photo and photothermal decomposition derivatives

• Thermal, photo, and photothermal aging of 2-nitrotoluene are performed.
• 2-Nitrosotoluene, toluene, 2-cresol, and 2-toluidine are the gas-phase decomposition products.
• Optical signatures of 2-nitrotoluene and the decomposition products are determined.
• NO and C (I) are observed in the spectrum of 2-nitrotoluene.
• 2-Cresol appears to be a good candidate to detect aged 2-nitrotoluene.

2-Nitrotoluene (2-NT) is subjected to thermal, photo, and photothermal aging to determine its gas-phase decomposition products via GC/MS. Besides 2-nitrotoluene, the following decomposition products are detected in the gas phase: toluene, 2-nitrosotoluene, 2-cresol, and 2-toluidine. Time resolved laser spectroscopy is used to identify the spectroscopic signatures of these gas-phase products. 2-Nitrotoluene photodissociates during the measurement, leading to the formation of NO and atomic carbon C I, and the observation of their characteristic spectroscopic signatures. Energy transfer between molecular nitrogen and NO is observed. A spectroscopic signature from 2-nitrotoluene in nitrogen with concentrations as low as about 100 ppt is observed. The toluene spectra show a broad emission centered at about 280 nm. The spectroscopic signature of 2-nitrosotoluene is similar to that of 2-NT, and the spectrum is dominated by emission from NO. However, unlike for 2-nitrotoluene, no C I is observed and energy transfer from nitrogen is not apparent. Even with a poorly matched excitation wavelength, the spectrum of 2-cresol shows a strong and broad emission peak centered at about 300 nm, which is promising for the detection of aged 2-nitrotoluene. No useful spectroscopic signatures are seen in the spectra of 2-toluidine.