Laser two-photon ionization spectroscopy: a new method for real-time monitoring of atmospheric pollutants

Abstract

Laser two-photon ionization spectroscopy is proposed as a selective and sensitive method of monitoring atmospheric pollutants in situ. The technique is demonstrated in the laboratory for a prototype molecule, aniline, in air at 1 atm. Advantages over existing laser-based methods are discussed, and an ultimate detection limit of <1 part in 10(11) is estimated using currently available technology.

New method for measuring low NO concentrations using laser induced two photon ionization

“…The general concept of ionization spectroscopy is well established. [13][14][15][16] The ionization method possesses significant advantages over the LIF method in detection efficiency. [17][18][19] In the ionization method, close to 100% of the ions can be collected, while in LIF the detection efficiencies are about 10 Ϫ4 due to the isotropical emission of photons.…”

Detection of time‐resolved photoionization currents from pesticide‐contaminated vegetation

“…17 Here, we report the first experimental attempt of direct surface probing of pesticide-contaminated vegetation by means of laser-induced multiphoton-ionization (MPI). [18][19][20][21][22][23][24] Several analytical applications based on this mode of material excitation have been developed. Many such studies have dealt with polycyclic aromatic hydrocarbons (PAH) in various systems of environmental and technological interest such as metal surfaces, [25][26] polar or apolar solvents, [27][28][29][30][31][32] as well as with a renewable microdroplet sampling of airborne particulates.…”

Fluorescence line narrowing spectrometry of polycyclic aromatic hydrocarbons in organic glasses

“…The broad bands in the spectra of polyatomic molecules in the gaseous phase are largely caused by unresolved rotational and over lapping sequence bands (18,19), Rotationally cooled fluorescence spectroscopy (13) is one promising technique for alleviating some of the spectral congestion and circumventing this selectivity problem. To obtain narrowed fluorescence bands, the proposed analytical method involves expension of a GC effluent through a "supersonic" nozzle.…”

“…Another novel gas phase technique utilizes resonant multiphoton photoionization (RMP) (19,20). By taking advantage of the high peak powers of pulsed lasers and sensitive current measurement instrumen tation, detection limits on the order of one femptogram (10""'^ g) are n possible (20).…”