Supersonic Jet Spectrometry

Franc and Placek [48] studied the chemical species of PS and polycarbonate (PC) resulting from supersonic jet spectrometry at temperatures up to 400 °C. The decomposition products from PS were styrene monomer, dimer, and trimer and toluene. The decomposition product from PC was p-cresol. 

This technique has been applied to the analysis of the surface of polymer blends such as miscible PC/PS blends [49] (See also Section 3.11.1.). 

Surface mass spectrometry (MS) techniques measure the masses of fragment ions that are ejected from the surface of a sample to identify the elements and molecules present. The techniques are complementary to electron spectroscopy since they provide extra absolute and surface sensitivity and give very specific molecular information. For unknown samples it is common to use a combination of electron spectroscopy and MS for surface characterisation. There are two methods of surface mass spectrometry used in polymer analysis SIMS and laser ionisation mass analysis (LIMA). Of these SIMS is by far the most important. 

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Lin CH, Fukii H, Imasaka T, et al. 1991. Synchronous scan luminescence techniques monitoring resonance and non-resonance fluorescence in supersonic jet spectrometry applied to anthracene derivatives. Anal Chem 63(14) 1433-1440. 

If Supersonic Jet Spectrometry. Imasaki et carried out supersonic jet spectrometry of chemical species resulting from the thermal decomposition of polystyrene at 400 C. Styrene monomer and its dimer and trimer, also toluene were identified in the decomposition products. 

Supersonic jet spectrometry of the chemical species resulting from the thermal decomposition of polycarbonate at temperatures up to 400 C showed that p-cresol is the... 

This chapter deals mainly with (multi)hyphenated techniques comprising wet sample preparation steps (e.g. SFE, SPE) and/or separation techniques (GC, SFC, HPLC, SEC, TLC, CE). Other hyphenated techniques involve thermal-spectroscopic and gas or heat extraction methods (TG, TD, HS, Py, LD, etc.). Also, spectroscopic couplings (e.g. LIBS-LIF) are of interest. Hyphenation of UV spectroscopy and mass spectrometry forms the family of laser mass-spectrometric (LAMS) methods, such as REMPI-ToFMS and MALDI-ToFMS. In REMPI-ToFMS the connecting element between UV spectroscopy and mass spectrometry is laser-induced REMPI ionisation. An intermediate state of the molecule of interest is selectively excited by absorption of a laser photon (the wavelength of a tuneable laser is set in resonance with the transition). The excited molecules are subsequently ionised by absorption of an additional laser photon. Therefore the ionisation selectivity is introduced by the resonance absorption of the first photon, i.e. by UV spectroscopy. However, conventional UV spectra of polyatomic molecules exhibit relatively broad and continuous spectral features, allowing only a medium selectivity. Supersonic jet cooling of the sample molecules (to 5-50 K) reduces the line width of their... 

Other techniques that have been used to determine polycyclic aromatic hydrocarbons in soil extracts include ELISA field screening [86], micellar elec-tr okinetic capillary chromatography [ 87], supersonic jet laser-induced fluorescence [88,89], fluorescence quenching [90], thermal desorption gas chromatography-mass spectrometry [81,90,100], microwave-assisted extraction [91], thermal desorption [92], immunochemical methods [93,94], electrophoresis [96], thin layer chromatography [95], and pyrolysis gas chromatography [35]. 

Recently, new 2D-methods for the analysis of complex mixtures have been developed for time-of-flight mass spectrometry (22), which could also be utilized in external ionization FTMS. Specifically, the combination of IR-laser desorption of nonvolatile neutrals, followed by adiabatic cooling to 2°K in a supersonic jet, and subsequent compound-selective Resonance-Enhanced Multiphoton Ionization (REMPI) could increase the role of FTMS in the analysis of biological mixtures. The coupling of supersonic jets to the external ion source would also be of interest in ion- and neutral cluster experiments. 

Most investigations of photoinduced electron transfer have been performed in condensed phases. Much less is known about conditions that permit the occurrence of intramolecular ET in isolated (collision-free) molecular D-A systems. A powerful method for this kind of study is the supersonic jet expansion teehnique (which was originally developed by Kantrowitz and Grey in 1951 [66]) combined with laser-induced fluorescence (LIF) spectroscopy and time-of-flight mass spectrometry (TOF-MS). On the other hand, the molecular aspects of solvation can be studied by investigations of isolated gas-phase solute-solvent clusters which are formed in a supersonic jet expansion [67] (jet cooling under controlled expansion conditions [68] permits a stepwise growth of size-selected solvation clusters [69-71]). The formation of van der Waals complexes between polyatomic molecules in a supersonic jet pro-... 

A number of less commonly used analytical techniques are available for determining PAHs. These include synchronous luminescence spectroscopy (SLS), resonant (R)/nonresonant (NR)-synchronous scan luminescence (SSL) spectrometry, room temperature phosphorescence (RTP), ultraviolet-resonance Raman spectroscopy (UV-RRS), x-ray excited optical luminescence spectroscopy (XEOL), laser-induced molecular fluorescence (LIMP), supersonic jet/laser induced fluorescence (SSJ/LIF), low- temperature fluorescence spectroscopy (LTFS), high-resolution low-temperature spectrofluorometry, low-temperature molecular luminescence spectrometry (LT-MLS), and supersonic jet spectroscopy/capillary supercritical fluid chromatography (SJS/SFC) Asher 1984 Garrigues and Ewald 1987 Goates et al. 1989 Jones et al. 1988 Lai et al. 1990 Lamotte et al. 1985 Lin et al. 1991 Popl et al. 1975 Richardson and Ando 1977 Saber et al. 1991 Vo-Dinh et al. 1984 Vo- Dinh and Abbott 1984 Vo-Dinh 1981 Woo et al. 1980). More recent methods for the determination of PAHs in environmental samples include GC-MS with stable isotope dilution calibration (Bushby et al. 1993), capillary electrophoresis with UV-laser excited fluorescence detection (Nie et al. 1993), and laser desorption laser photoionization time-of-flight mass spectrometry of direct determination of PAH in solid waste matrices (Dale et al. 1993). 

Lubman, D. M., and Li, Liang (1990). Resonant two-photon ionization spectroscopy of biological molecules in supersonic jets volatilized by pulsed laser desorption. In Lasers and Mass-Spectrometry (ed. D. M. Lubman), pp. 352-382. Oxford University Press, New York. 

Synchrotron radiation of 115 to 170 nm has been used to dissociate SiH4 in a pulsed supersonic free jet, and the abundance of SiH2 was measured by quadrupole mass spectrometry using 11 V sub-ionization threshold electron-impact energy301. The possible detection of SiH2 in the outer envelope of a stellar object has been reported302. 

A plasma source was coupled to a TOF-MS as early as the 1960s, when workers at Bendix [12] used such an arrangement to analyze the chemical species in a plasma jet. The instrument utilized a pulsed supersonic inlet probe similar to that found in current inductively coupled plasma mass spectrometry (ICP-MS) quadru-pole instruments and employed a TOF-MS that was oriented at a 90° angle to the input ion beam. More importantly, however, it used a pulsed extraction field to extract ions from the plasma source and accelerate them into the flight tube. It is this concept of injecting discrete ion bunches into the TOF-MS analyzer that has been almost ubiquitously employed by workers using continuous ion sources [17,18]. 

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