Resonance enhanced multiphoton ionisation

Other MS-fingerprinting techniques that are in commercial development are based on atmospheric pressure ionisation (API), resonance-enhanced multiphoton ionisation (REMPI) TOE and proton-transfer reaction (PTR). They are rapid, sensitive and specific and allow measurements in real time and may play an increasingly important role in the future development of electronic noses and tongues. 

MOS metal oxide sensor, MOSFET metal oxide semiconductor field-effect transistor, IR infrared, CP conducting polymer, QMS quartz crystal microbalance, IMS ion mobility spectrometry, BAW bulk acoustic wave, MS mass spectrometry, SAW siuface acoustic wave, REMPI-TOFMS resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry... 

Fig. 15.14 Analytical techniques for time-resolved headspace analysis. An electronic nose can be used as a low-cost process-monitoring device, where chemical information is not mandatory. Electron impact ionisation mass spectrometry (EI-MS) adds sensitivity, speed and some chemical information. Yet, owing to the hard ionisation mode, most chemical information is lost. Proton-transfer-reaction MS (PTR-MS) is a sensitive one-dimensional method, which provides characteristic headspace profiles (detailed fingerprints) and chemical information. Finally, resonance-enhanced multiphoton ionisation (REMPI) TOFMS combines selective ionisation and mass separation and hence represents a two-dimensional method. (Adapted from [190])...

Resonance-Enhanced Multiphoton Ionisation Time-of-Flight Mass Spectrometry... 

Fig. 9.2. Excitations schemes for resonantly enhanced multiphoton ionisation using three and four photons (schematic) (after J.-P. Connerade and A.M. Lane [385]).

The use of resonance enhanced multiphoton ionisation (REMPI) spectroscopy Hnked to time of flight mass spectroscopy has been demonstrated in on-Hne monitoring of combustion by-products in industrial flue gases [14] and in a research project dedicated to the analysis of coffee roasting processes [15]. REMPI is a highly... 

The competition between dissociation and fluorescence produces such a dramatic effect in this case because the radiative lifetime is very long (- 23 ysec). The C state of H2O furnishes a very different example. The photodissociation dynamics of this state have been probed using multiphoton excitation, with detection either of ions or of fluorescence. The 3+1 resonance enhanced multiphoton ionisation spectra of the C states of H2O and D2O are dominated by levels with low K, and particularly (Ashfold, Bayley and Dixon 1984). The two-... 

The product state distribution can be measured directly, for example by laser induced fluorescence (LIF) or resonance enhanced multiphoton ionisation (REMPI). Both of these techniques yield the quantum specific density of AB molecules that are created in the dissociation process. However, these methods can be applied only to a limited number of molecules. Whereas LIF is essentially restricted to a few diatomic molecules, REMPI allows in a few favoured cases also the state selective detection of larger molecules. 

Mass spectrometric in-situ determination of NO2 in gas mixtures by resonance enhanced multiphoton ionisation,... 

Gasmi K, Al-Tuwirqi RM, Skowronek S, Telle HH, Gonzalez Urena A. 2003. Rotationally resolved (1 + 1 ) resonance-enhanced multiphoton ionisation (REMPI) of CaR (R = H,D) in supersonic... 

Laser desorption/Iaser post-ionisation (two-shot LDI) can display either non-specific detection (using non-resonant single-photon ionisation) or species-specific detection (using resonance-enhanced multiphoton ionisation). By exercising both of these options, complicated mixtures can be analysed for surface species. As efficiency of mass spectral analysis is greatly enhanced by ionising the... 

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