Shu J, Bar I, Rosenwaks S
Department of Physics, Ben Gurion University of the Negev, Beer Sheva 84105, Israel.
Appl Opt. 1999 Jul 20;38(21):4705-10. doi: 10.1364/ao.38.004705.
Trace concentrations of 1, 4-dinitrobenzene (DNB) are detected by a combination of laser photolysis and laser-induced fluorescence. A one-color laser is applied to induce DNB photodissociation and for subsequent detection of NO photofragments by excitation and emission through A(v' =0) <-- X(v" = 0 - 2) and A(v' =0) --> X(v" = 0,1) transitions, respectively. The resulting NO rovibrational excitation spectra serve as markers for the presence of DNB. The NO is produced in vibrational ground and excited states with peak height ratios of (v" = 0):(v" = 1):(v" = 2) = 1:0.5:0.13. The limits of detection of DNB mixed with 100 or 500 Torr of air with v" = 2 excitation at 248 nm are 13 and 11 parts in 10(9) by weight, respectively, for a 30-s integration time. The application of this scheme for DNB detection has the advantage that no ambient ground state NO interferes and that the fluorescence is collected at shorter wavelengths than the exciting radiation, precluding background fluorescence.
通过激光光解和激光诱导荧光相结合的方法来检测痕量浓度的1,4-二硝基苯（DNB）。使用单色激光诱导DNB光解离，并通过分别经由A(v' =0) <-- X(v" = 0 - 2)和A(v' =0) --> X(v" = 0,1)跃迁进行激发和发射，随后检测NO光碎片。所得到的NO振转激发光谱可作为DNB存在的标记。产生的NO处于振动基态和激发态，其峰高比为(v" = 0):(v" = 1):(v" = 2) = 1:0.5:0.13。对于在248 nm处用v" = 2激发、与100或500 Torr空气混合的DNB，在30 s积分时间下，检测限分别为重量比的10⁹分之13和11。该DNB检测方案的优点在于没有环境基态NO的干扰，并且荧光在比激发辐射更短的波长处收集，从而排除了背景荧光。
