scholarly journals Coagulation of combustion generated nanoparticles and their measurement behind vehicle engines: can they play a role as atmospheric pollutants?

2005 ◽  
Vol 5 (3) ◽  
pp. 3847-3872
Author(s):  
H.-H. Grotheer ◽  
T. Gonzalez Baquet ◽  
M. Thierley ◽  
H. Pokorny ◽  
M. Aigner
Keyword(s):  
Flow Reactor ◽  
Direct Injection ◽  
Atmospheric Pollutants ◽  
High Rate ◽  
Rate Coefficients ◽  
Inlet System ◽  
Source Rate ◽  
Fast Flow ◽  
Droplet Fragmentation ◽  
Fast Flow Reactor

Abstract. Based on photoionisation mass spectrometry two types of experiments were carried out. (i) In a fast flow reactor coupled to a low pressure flame as a particle source, rate coefficients for the coagulation of primary nanoparticles were measured through variation of the reactor residence time. The results are kc (350K) = 3.5x10-10cm3/s and kc (573K) = 1.1x10-9cm3/s, i.e. very high rate coefficients. It was also shown that coagulated nanoparticles can have masses beyond 50ku, corresponding to equivalent diameters between 4 to 5nm. These particles are easily fragmented during photoionisation. (ii) Using a second and mobile photoionisation mass spectrometer equipped with a fast flow inlet system, measurements were carried out behind three different vehicle engines, a two-stroke scooter engine, a four-stroke motorbike engine and a DI (direct injection) gasoline research engine. In all cases ion signals around 1000u were found that are clearly dependent on engine conditions. In the case of the DI engine, they correlate with the smoke number. These signals cannot be explained by PAHs due to their low volatility at the respective masses. Major contributions of soot or droplet fragmentation were ruled out through additional experiments using a heated inlet line and a filter. Consequently, these signals are interpreted as fragments of coagulated nanoparticles.

Reaction Kinetics of Ground State Fluorine, F(2P), Atoms. I. Measurement of Fluorine Atom Concentrations and the Rates of Reactions F + CHF3 and F + Cl2 using Mass Spectrometry

1973 ◽  
Vol 51 (21) ◽  
pp. 3596-3604 ◽  
Author(s):  
Michael A. A. Clyne ◽  
Donald J. McKenney ◽  
Ronald. F. Walker
Keyword(s):  
Mass Spectrometry ◽  
Reaction Kinetics ◽  
Ground State ◽  
Fluorine Atom ◽  
Flow Reactor ◽  
Bimolecular Reaction ◽  
Inlet System ◽  
Fast Flow ◽  
Kinetics Of ◽  
Fast Flow Reactor

Reactions of F(2P) atoms generated by a 2.45 GHz discharge in dilute F2 + He mixtures have been studied mass spectrometrically with a beam inlet system from a fast flow reactor. F atom concentrations have been measured from the consumption of Cl2 in the simple and extremely rapid bimolecular reaction 1[Formula: see text]k1 was determined to be (1.1 ± 0.3) × 10−10 cm3 molecule−1 s−1 at 300 °K.Rate measurements for the reaction 2, which forms CF3 radicals, are reported, over the range 301 to 667 °K,[Formula: see text][Formula: see text]A less detailed survey of the rates at 298 °K of a series of reactions of F with H2, CH4, CH3Cl, CH2Cl2, and CHCl3, is also given; in these cases, the source of F was a discharge in CF4 + Ar, and [F] was measured by titration with ClNO.

Tubular Fast Flow Reactor for High Temperature Gas Kinetic Studies

1972 ◽  
Vol 43 (5) ◽  
pp. 726-730 ◽  
Author(s):  
Arthur Fontijn ◽  
Shelby C. Kurzius ◽  
James J. Houghton ◽  
John A. Emerson
Keyword(s):  
High Temperature ◽  
Flow Reactor ◽  
Kinetic Studies ◽  
Fast Flow ◽  
Fast Flow Reactor ◽  
High Temperature Gas

Gas-phase chemical kinetics of small metal clusters: developmen and characterization of a fast-flow reactor for neutral clusters

1993 ◽  
Vol 26 (S1) ◽  
pp. 168-170 ◽  
Author(s):  
L. Lian ◽  
F. Akhtar ◽  
J. M. Parsons ◽  
P. A. Hackett ◽  
D. M. Rayner
Keyword(s):  
Gas Phase ◽  
Chemical Kinetics ◽  
Metal Clusters ◽  
Flow Reactor ◽  
Fast Flow ◽  
Kinetics Of ◽  
Fast Flow Reactor ◽  
Phase Chemical

High-temperature fast-flow reactor study of Sn/N2O chemiluminescence

1975 ◽  
Vol 34 (2) ◽  
pp. 398-402 ◽  
Author(s):  
William Felder ◽  
Arthur Fontijn
Keyword(s):  
High Temperature ◽  
Flow Reactor ◽  
Fast Flow ◽  
Fast Flow Reactor

Tubular fast-flow reactor studies at high temperatures. Kinetics of the reaction

1974 ◽  
Vol 27 (3) ◽  
pp. 365-368 ◽  
Author(s):  
A. Fontijn ◽  
W. Felder ◽  
J.J. Houghton
Keyword(s):  
High Temperatures ◽  
Flow Reactor ◽  
Fast Flow ◽  
Kinetics Of ◽  
Fast Flow Reactor

The Reaction of Hydrogen Atoms with Silyl Radicals; the Decomposition Pathways of Chemically Activated Silanes

1983 ◽  
Vol 38 (8) ◽  
pp. 896-908 ◽  
Author(s):  
K. Wörsdorfer ◽  
B. Reimann ◽  
P. Potzinger
Keyword(s):  
Vibrational Energy ◽  
Flow Reactor ◽  
Hydrogen Abstraction ◽  
Hydrogen Atoms ◽  
Experimental Conditions ◽  
Silyl Radicals ◽  
Subsequent Step ◽  
Temperature Rate ◽  
Fast Flow ◽  
Fast Flow Reactor

Abstract The reactions of hydrogen atoms with silane and the methylated silanes - with the exception of tetramethylsilane -have been investigated in a fast flow reactor. Under our experimental conditions hydrogen abstraction from the Si-H bond is followed by combination of hydrogen atoms with the corresponding silyl radicals. The molecules formed in this way are activated by about 375 kJ/mol of vibrational energy. Two decomposition channels have been unequivocally identified, namely the elimination of molecular hydrogen and of methane, both with concomittant formation of the respective silylenes. In a subsequent step, silylene inserts into the substrate under formation of disilanes. With increasing degree of methylation. stabilization of the activated molecule competes with decomposition and dominates the kinetics in the case of trimethylsilane. With methyl -and dimethyl-silane, methyl radicals are observed as an additional reaction product. On the basis of RRKM calculations it is unlikely that they originate from a direct decomposition of the activated molecules.Absolute values for the room temperature rate constants of the abstraction reactions are given; for H+CH3SiH3, Arrhenius parameters have been determined.

Free radicals by mass spectrometry. XL. Primary processes and transient intermediates in the mercury (3P1) photosensitization of hydrazine

1969 ◽  
Vol 47 (8) ◽  
pp. 1391-1393 ◽  
Author(s):  
A. Jones ◽  
F. P. Lossing
Keyword(s):  
Mass Spectrometry ◽  
Free Radicals ◽  
Mass Spectrometer ◽  
Direct Evidence ◽  
Flow Reactor ◽  
Low Pressure ◽  
Primary Decomposition ◽  
Fast Flow ◽  
Transient Intermediates ◽  
Fast Flow Reactor

The low pressure mercury (3P1) photosensitized decomposition of hydrazine has been studied at 55 °C in a fast flow reactor coupled to a mass spectrometer. Direct evidence was obtained for the participation of N2H2, N2H3, NH2, and NH in the decomposition, and two primary decomposition modes were established[Formula: see text]

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