Determination of Photoionization Cross-Sections of Different Organic Molecules Using Gas Chromatography Coupled to Single-Photon Ionization (SPI) Time-of-Flight Mass Spectrometry (TOF-MS) with an Electron-Beam-Pumped Rare Gas Excimer Light Source (EBEL): Influence of Molecular Structure and Analytical Implications

2011 ◽  
Vol 65 (7) ◽  
pp. 806-816 ◽  
Author(s):  
Markus S. Eschner ◽  
Ralf Zimmermann
Keyword(s):  
Molecular Structure ◽  
Cross Sections ◽  
Organic Molecules ◽  
Single Photon ◽  
Rare Gas ◽  
Flight Mass Spectrometry ◽  
Photon Ionization ◽  
Tof Ms ◽  
Excimer Light Source

scholarly journals Determination of the absorption cross-sections of higher order iodine oxides at 355 nm and 532 nm

2020 ◽  
Author(s):  
Thomas R. Lewis ◽  
Juan Carlos Gómez Martin ◽  
Mark A. Blitz ◽  
Carlos A. Cuevas ◽  
John M. C. Plane ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Atmospheric Chemistry ◽  
Absorption Cross Section ◽  
Absorption Cross ◽  
Time Resolved ◽  
Flight Mass Spectrometry ◽  
Iodine Oxides ◽  
Photo Ionization

Abstract. Iodine oxides (IxOy) play an important role in the atmospheric chemistry of iodine. They are initiators of new particle formation events in the coastal and polar boundary layer and act as iodine reservoirs in tropospheric ozone-depleting chemical cycles. Despite the importance of the aforementioned processes, the photochemistry of these molecules has not been studied in detail previously. Here, we report the first determination of the absorption cross sections of IxOy, x = 2, 3, 5, y = 1–12 at λ = 355 nm by combining pulsed laser photolysis of I2/O3 gas mixtures in air with time-resolved photo-ionization time-of-flight mass spectrometry, using NO2 actinometry for signal calibration. The oxides selected for absorption cross section determinations are those presenting the strongest signals in the mass spectra, where signals containing 4 iodine atoms are absent. The method is validated by measuring the absorption cross section of IO at 355 nm, σ355 nm, IO = (1.2 ± 0.1) ×  10–18 cm2, which is found to be in good agreement with the most recent literature. The results obtained are: σ355 nm, I2O3 

Using Spectrum-Effect Relationships Coupled with LC–TOF–MS to Screen Anti-arrhythmic Components of the Total Flavonoids in Hypericum attenuatum Extracts

2020 ◽  
Author(s):  
Yufei Feng ◽  
Lin Teng ◽  
Yanli Wang ◽  
Yanyu Gao ◽  
Yuxuan Ma ◽  
...  
Keyword(s):  
Total Flavonoids ◽  
Universal Model ◽  
Bioactive Constituents ◽  
Flight Mass Spectrometry ◽  
Chemical Fingerprints ◽  
Relationship Of ◽  
The Relationship ◽  
Spectrum Effect ◽  
Tof Ms

Abstract This research explored the HPLC fingerprints of Hypericum attenuatum Choisy, which has anti-arrhythmic activity. HPLC was adopted to perform a determination of chemical fingerprints of H. attenuatum specimens acquired through seven distinct sources. The anti-arrhythmic activity of each H. attenuatum sample was obtained through pharmacodynamics experiments in animals. A regression analysis and correlation analysis were utilized to calculate the relationship of the peak and pharmacological effectiveness with the identified peak. Peaks numbered 5, 7, 13 and 14 in the fingerprint were regarded as the likely anti-arrhythmic agents. The fingerprint was compared with reference standards for identification of the correlative peaks. Liquid chromatography–time-of-flight–mass spectrometry was applied to identify its structure. As a consequence, a universal model was established for the utilization of HPLC to investigate anti-arrhythmic activity and the spectrum-effect relationship among H. attenuatum. This model is available for the discovery of the major bioactive constituents of Hypericum.

Single photon ionization time-of-flight mass spectrometry with a windowless RF-discharge lamp for high temporal resolution monitoring of the initial stage of methanol-to-olefins reaction

The Analyst ◽  
2019 ◽  
Vol 144 (4) ◽  
pp. 1104-1109 ◽  
Author(s):  
QingYun Li ◽  
Lei Hua ◽  
Yuanyuan Xie ◽  
Jichun Jiang ◽  
Hanwei Li ◽  
...  
Keyword(s):  
Single Photon ◽  
Rapid Analysis ◽  
Rf Discharge ◽  
High Temporal Resolution ◽  
Ionization Time ◽  
Broad Application ◽  
Flight Mass Spectrometry ◽  
Initial Stage ◽  
Highly Sensitive ◽  
Photon Ionization

The highly sensitive TOFMS with a time resolution of 0.5 s, has broad application in the fields of on-site rapid analysis, especially the major industrial reaction process monitoring.

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