Tunable single-photon ionization TOF mass spectrometry using laser-produced plasma as the table-top VUV light source

Abstract

Here we report on a laser plasma-based tunable VUV photoionization time-of-flight (TOF) mass spectrometer conceived mainly to study complex gaseous mixtures. Ionizing photons at tunable vacuum UV (VUV) wavelengths are generated by a gas-target laser-produced plasma, spectrally dispersed in the range 100 -160 nm and efficiently focused onto a sample molecular beam. As a test case, we studied the exhaust gas of a four-stroke moped, a typical example of a complex gaseous mixture. Due to the VUV "soft" ionization, the mass spectra are less congested and more easily interpretable. Substituted benzene derivatives are found to give the most intense signals. Several aliphatic hydrocarbons are also detected. The use of tunable VUV radiation allowed the investigation of the contribution of isomers in the mass spectrum from the onset and shape of the photoionization efficiency spectra. Semiquantitative analysis was performed using known literature data detailing the photoionization cross sections. Our findings suggest that using combined data on the mass/photoionization efficiency spectra may be very helpful for a comprehensive analysis of complex gaseous mixtures. (J Am Soc

Photoionisation and structures of jet-formed toluene clusters

“…A detailed description of the experimental set-up has been reported in a previous paper [16]. However, for sake of completeness, a brief description is reported here.…”

“…4821G). The mass resolution was m/Dm % 200 at m/z = 92 by using a constant extraction field of 200 V/cm and could be increased at m/Dm % 420 at m/z = 128 (naphthalene) by using pulsed/delayed extraction fields [16].…”

“…This Letter aims to compare experimental IP values of small (TOL) n clusters with those that were predicted by numerical modelling to shed light on the earliest seeding structures. To this end, we have used a tunable vacuum ultraviolet radiation from a laser produced plasma (LPP), we recently developed as soft single photon ionisation (SPI) source and coupled to time of flight mass spectrometry (TOF-MS) [14][15][16]. First, we experimentally determined the photoionisation efficiency (PIE) curves of toluene clusters (TOL) n that were spectrally resolved in the 8-10 eV range of ionising photon energy.…”

UV Photoionization of Sodium‐Doped Formic Acid Clusters

“…A schematic of the experimental apparatus is shown in Figure 1, whereas the full technical details of the experimental setup of the Na-doping are reported in. [8,[25][26][27] For clarity, only a brief description of the basic details of apparatus setup is given here. The main hardware is composed of two vacuum chambers, independently evacuated by two turbomolecular pumps (1000 l/sec) and connected to each other through a 3 mm hole.…”

Post Discharge Chemistry of Aromatic Molecules in Rare Gas

“…DiPalma et al have reported on the use and characterization of this method [54][55][56][57]. They have furthermore demonstrated its use to detect IPs of products of engine exhaust, with detection sensitivities comparable to VUV synchrotrons of *1 ppmv [55].…”