Discharge flow-mass spectrometry

Fig. 2.22. Temperature and pressure dependence of k 2 using a combination of discharge flow/mass spectrometry, flash photolysis/PIMS, and flash photolysis/UV absorption techniques. The solid lines represent the giobai best fits of all the data as outlined in subsequent...

The abbreviations used for techniques are DF-RF discharge flow-resonance fluorescence DF-RA discharge flow-resonance absorption DF-ESR discharge flow-esr detection DF-LMR discharge flow with laser magnetic resonance detection of OH DF-MS discharge flow-mass spectrometry FP-KS flash photolysis-kinetic spectroscopy FP-RA flash photolysis-resonance absorption FP-RF flash photolysis-resonance fluorescence MPS modulation-phase shift ... 

Mechanism, in the discharge flow-mass spectrometry studies of Morris, Stedman, and Niki (81), mass peaks corresponding to the OH-alkene adducts were observed for ethene and propene. 

DSF-VA discharge stopped flow - visible absorption DF-VA discharge flow - visible absorption, p < 5 Torr DF-MS discharge flow - mass spectrometry EC-RR environmental chamber - relative rate RR relative rate, atmospheric pressure of air PR-KS pulse radiolysis - kinetic spectroscopy... 

DF-MS/RF discharge flow-mass spectrometry / resonance fluorescence... 

The kinetics of the reaction of NO3 with the following molecules have been investigated using the discharge-flow mass spectrometry method 2,3 dimethyl-2, butene ((CH3)2C=C(CH3)2), 1,3 butadiene (CH2=CH-CH=CH2), 2 methyl-1,3 butadiene (CH2=C(CH3)-CH=CH2, isoprene) and 2,3 dimethyl-1,3 butadiene (CH2=C(CH3)-C(CH3) = CH2). 

The rate coefficients have been measured by a relative rate technique by Taketani et al. (2006), by pulsed laser photolysis by Albaladejo et al. (2003b) and Takahashi et al. (2007), and by discharge flow-mass spectrometry by Aranda et al. (2004). See table V-B-13. The two latest measurements exceed the earlier measurements by a factor of about 2. An unweighted mean of these two determinations is recommended, giving k(298) = 1.44x 10 ° cm molecule" s with an uncertainty of 40%. The positive temperature dependence obtained by Aranda et al. is very large for a reaction of this type and gives an unrealistically large A-factor. 

Most ion-molecule techniques study reactivity at pressures below 1000 Pa however, several techniques now exist for studying reactions above this pressure range. These include time-resolved, atmospheric-pressure, mass spectrometry optical spectroscopy in a pulsed discharge ion-mobility spectrometry [108] and the turbulent flow reactor [109]. 

FFF Field-flow fractionation GD-(MS) Glow-discharge (mass spectrometry)... 

A.J. BeU and S.K. Ross, Reverse flow continuous corona discharge ionization. International Journal of Mass Spectrometry 218(2) (2002) LI—L6, also found in part at International Journal for Ion Mobility Spectrometry 5(3) (2002) 95—99. 

Note The acronyms used here are OSPED (optical spectroscopy in a pulsed electrical discharge), FAMS (flowing afterglow mass spectrometry), SIFT (selected ion flow tube), TRAPI (time-resolved atmospheric pressure ionization mass spectrometry), PHPMS (pulsed high-pressure ionization mass spectrometry), ICRMS (ion cyclotron resonance mass spectrometry), and ADO (averaged dipole orientation collision rate theory). 

Figure 22-19 (a) Atmospheric pressure chemical ionization interface between a liquid chromatography column and a mass spectrometer. A fine aerosol Is produced by the nebulizing gas flow and the heater. The electric discharge from the corona needle creates gaseous ions from the analyte. [Adapted from E. C. Huang, T. Wachs, J. J. Conboy, and J. D. Henion, Atmospheric Pressure Ionization Mass Spectrometry," Anal. Chem. 1990,62,713A ] (b) Atmospheric pressure chemical ionization probe. [Courtesy Shimadzu Scientific Instruments, Columbia, MD.J... 

E E(t) EDM EDTA EDX EHD EKI EO EOF ESI-MS Ez Activation energy Exit-age distribution function Electro-discharge machining Ethylene-diamine-tetraacetic acid Energy dispersive X-ray Electrohydrodynamic Electrokinetic instability Electroosmotic-Electroosmotic flow Electrospray ionization mass spectrometry Electric field... 

The reactions of hydrogen peroxide with both O and H atoms have been studied by Albers et al. [74] in the temperature range 300—800 K, using a discharge-flow system. The H2O2 was always added downstream of the discharge. Analysis was by ESR and mass spectrometry. 

A more sophisticated, though less common version of PTR-MS is selected ion flow tube mass spectrometry (SIFT-MS). In this technique, a mixture of reagent ions is generated in a gas discharge ion source and then a Q mass filter is used to select one reagent ion, which is then injected into an inert carrier gas (usually He), for... 

Monks, P. S., L. J. Stief, D. C. Tardy, J. F. Liebman, Z. Zhang, S. -C. Kuo and R. B. Klemm Discharge flow-photoionization mass spectrometrie study of HOI Photoionization efficiency spectrum and ionization energy, / Phys Chem, 99 (1995) 16566-16570. 

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