scholarly journals Proton transfer dynamics modified by CH-stretching excitation

2020 ◽  
Vol 22 (22) ◽  
pp. 12382-12388 ◽  
Author(s):  
Tim Michaelsen ◽  
Björn Bastian ◽  
Patrick Strübin ◽  
Jennifer Meyer ◽  
Roland Wester
Keyword(s):  
Physical Chemistry ◽  
Proton Transfer ◽  
Reaction Kinetics ◽  
Fundamental Goal ◽  
Kinetics And Dynamics ◽  
Rovibrational States ◽  
Gaining Insight

Gaining insight how specific rovibrational states influence reaction kinetics and dynamics is a fundamental goal of physical chemistry.

scholarly journals Validity and limitations of simple reaction kinetics to calculate concentrations of organic compounds from ion counts in PTR-MS

2019 ◽  
Vol 12 (11) ◽  
pp. 6193-6208 ◽  
Author(s):  
Rupert Holzinger ◽  
W. Joe F. Acton ◽  
William J. Bloss ◽  
Martin Breitenlechner ◽  
Leigh R. Crilley ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Reaction Kinetics ◽  
Transfer Reaction ◽  
Performance Status ◽  
Calibration Method ◽  
Proton Transfer Reaction ◽  
Rural Site ◽  
Water Molecules ◽  
Simple Reaction ◽  
Wide Range

Abstract. In September 2017, we conducted a proton-transfer-reaction mass-spectrometry (PTR-MS) intercomparison campaign at the CESAR observatory, a rural site in the central Netherlands near the village of Cabauw. Nine research groups deployed a total of 11 instruments covering a wide range of instrument types and performance. We applied a new calibration method based on fast injection of a gas standard through a sample loop. This approach allows calibrations on timescales of seconds, and within a few minutes an automated sequence can be run allowing one to retrieve diagnostic parameters that indicate the performance status. We developed a method to retrieve the mass-dependent transmission from the fast calibrations, which is an essential characteristic of PTR-MS instruments, limiting the potential to calculate concentrations based on counting statistics and simple reaction kinetics in the reactor/drift tube. Our measurements show that PTR-MS instruments follow the simple reaction kinetics if operated in the standard range for pressures and temperature of the reaction chamber (i.e. 1–4 mbar, 30–120∘, respectively), as well as a reduced field strength E∕N in the range of 100–160 Td. If artefacts can be ruled out, it becomes possible to quantify the signals of uncalibrated organics with accuracies better than ±30 %. The simple reaction kinetics approach produces less accurate results at E∕N levels below 100 Td, because significant fractions of primary ions form water hydronium clusters. Deprotonation through reactive collisions of protonated organics with water molecules needs to be considered when the collision energy is a substantial fraction of the exoergicity of the proton transfer reaction and/or if protonated organics undergo many collisions with water molecules.

scholarly journals Single-molecule chemical reaction reveals molecular reaction kinetics and dynamics

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Yuwei Zhang ◽  
Ping Song ◽  
Qiang Fu ◽  
Mingbo Ruan ◽  
Weilin Xu
Keyword(s):  
Reaction Kinetics ◽  
Chemical Reaction ◽  
Single Molecule ◽  
Molecular Reaction ◽  
Kinetics And Dynamics

scholarly journals Validity and limitations of simple reaction kinetics to calculate concentrations of organic compounds from ion counts in PTR-MS

2019 ◽  
Author(s):  
Rupert Holzinger ◽  
W. Joe F. Acton ◽  
William J. Bloss ◽  
Martin Breitenlechner ◽  
Leigh R. Crilley ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Reaction Kinetics ◽  
Transfer Reaction ◽  
Performance Status ◽  
Calibration Method ◽  
Proton Transfer Reaction ◽  
Rural Site ◽  
Water Molecules ◽  
Simple Reaction ◽  
Wide Range

Abstract. In September 2017, we conducted the Proton-transfer-reaction mass-spectrometry (PTR-MS) Intercomparison campaign at CABauw (PICAB), a rural site in central Netherlands. Nine research groups deployed a total of eleven instruments covering a wide range of instrument types and performance. We applied a new calibration method based on fast injection of a gas standard through a sample loop. This approach allows calibrations on time scales of seconds and within a few minutes an automated sequence can be run allowing to retrieve diagnostic parameters that indicate the performance status. We developed a method to retrieve the mass dependent transmission from the fast calibrations, which is an essential characteristic of PTR-MS instruments, limiting the potential to calculate concentrations based on counting statistics and simple reaction kinetics in the reactor/drift tube. Our measurements show that PTR-MS instruments follow the simple reaction kinetics if operated in the standard range for pressures and temperature of the reaction chamber (i.e. 1–4 mbar, 30–120 ℃, respectively), and a reduced field strength E/N in the range of 100–160 Td. If artefacts can be ruled out, it becomes possible to quantify the signals of uncalibrated organics with accuracies better than ±30 %. The simple reaction kinetics approach produces less accurate results at E/N levels below 100 Td, because significant fractions of primary ions form water hydronium clusters. De-protonation through reactive collisions of protonated organics with water molecules need to be considered when the collision energy is a substantial fraction of the exoergicity of the proton transfer reaction, and/or if protonated organics undergo many collisions with water molecules.

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