Photo-Ionization Time Delay in Linearly Extended π-Conjugated Molecular Systems

2021 ◽  
Author(s):  
Deep Mukherjee ◽  
Upendra Harbola
Keyword(s):  
Time Delay ◽  
Ionization Time ◽  
Molecular Systems ◽  
Photo Ionization

scholarly journals Photo Ionization Time Delay in Molecular Hydrogen

2015 ◽  
pp. 36-39
Author(s):  
S. Heuser ◽  
M. Sabbar ◽  
R. Boge ◽  
M. Lucchini ◽  
L. Gallmann ◽  
...  
Keyword(s):  
Time Delay ◽  
Molecular Hydrogen ◽  
Ionization Time ◽  
Photo Ionization

scholarly journals Hyphenation of a EC / OC thermal–optical carbon analyzer to photo-ionization time-of-flight mass spectrometry: an off-line aerosol mass spectrometric approach for characterization of primary and secondary particulate matter

2015 ◽  
Vol 8 (8) ◽  
pp. 3337-3353 ◽  
Author(s):  
J. Diab ◽  
T. Streibel ◽  
F. Cavalli ◽  
S. C. Lee ◽  
H. Saathoff ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Source Apportionment ◽  
Mass Spectrometer ◽  
Mass Spectrometric ◽  
Wood Combustion ◽  
Ionization Time ◽  
Aerosol Mass ◽  
Photon Ionization ◽  
Photo Ionization

Abstract. Source apportionment and characterization of primary and secondary aerosols remains a challenging research field. In particular, the organic composition of primary particles and the formation mechanism of secondary organic aerosols (SOAs) warrant further investigations. Progress in this field is strongly connected to the development of novel analytical techniques. In this study an off-line aerosol mass spectrometric technique based on filter samples, a hyphenated thermal–optical analyzer photo-ionization time-of-flight mass spectrometer (PI-TOFMS) system, was developed. The approach extends the capability of the widely used particulate matter (PM) carbon analysis (for elemental / organic carbon, EC / OC) by enabling the investigation of evolved gaseous species with soft and selective (resonance enhanced multi-photon ionization, REMPI) and non-selective photo-ionization (single-photon ionization, SPI) techniques. SPI was tuned to be medium soft to achieve comparability with results obtained by the electron ionization aerosol mass spectrometer (AMS). Different PM samples including wood combustion emission samples, smog chamber samples from the reaction of ozone with different SOA precursors, and ambient samples taken at Ispra, Italy, in winter as well as in summer were tested. The EC / OC–PI-TOFMS technique increases the understanding of the processes during thermal–optical analysis and identifies marker substances for the source apportionment. Composition of oligomeric or polymeric species present in PM can be investigated by the analysis of the thermal breakdown products. In the case of wood combustion, in addition to the well-known markers at m/z ratios of 60 and 73, two new characteristic masses (m/z 70 and 98) have been revealed as potentially linked to biomass burning. All four masses were also the dominant signals in an ambient sample taken in winter time in Ispra, Italy, confirming the finding that wood burning for residential heating is a major source of PM in winter at this location. The summer sample from the same location showed no influence of wood burning, but seems to be dominated by SOAs, which was confirmed from the comparison with chamber experiment samples. The experiments conducted with terpenes as precursors showed characteristic masses at m/z 58 and 82, which were not observable in any other emission samples and could serve as a marker for SOA from terpenes.

scholarly journals Hyphenation of a EC / OC thermal-optical carbon analyzer to photo ionization time-of-flight mass spectrometry: a new off-line aerosol mass spectrometric approach for characterization of primary and secondary particulate matter

2015 ◽  
Vol 8 (1) ◽  
pp. 269-308 ◽  
Author(s):  
J. Diab ◽  
T. Streibel ◽  
F. Cavalli ◽  
S. C. Lee ◽  
H. Saathoff ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Source Apportionment ◽  
Mass Spectrometer ◽  
Time Of Flight ◽  
Mass Spectrometric ◽  
Wood Combustion ◽  
Ionization Time ◽  
Aerosol Mass ◽  
Wood Burning ◽  
Photo Ionization

Abstract. Source apportionment and exposure of primary and secondary aerosols remains a challenging research field. In particular, the organic composition of primary particles and the formation mechanism of secondary organic aerosols (SOA) warrant further investigations. Progress in this field is strongly connected to the development of novel analytical techniques. In this study an off-line aerosol mass spectrometric technique based on filter samples, a hyphenated thermal/optical analyzer-photo ionization time of flight mass spectrometer (PI-TOFMS) system, was developed. The approach extends the capability of the widely used PM carbon analysis (for elemental/organic carbon (EC / OC)) by enabling the investigation of evolved gaseous species with soft and selective (resonance enhanced multiphoton ionization, REMPI) and non-selective photo ionization (single photon ionization, SPI) techniques. SPI was tuned to be medium soft to achieve comparability with results obtained by electron ionization (EI) aerosol mass spectrometer (AMS). Different PM samples including wood combustion emission samples, smog chamber samples from the reaction of ozone with different SOA precursors, and ambient samples taken at Ispra, Italy in winter as well as in summer were tested. The EC / OC-PI-TOFMS technique increases the understanding of the processes during the thermal/optical analysis and identifies marker substances for the source apportionment. Composition of oligomeric or polymeric species present in PM can be investigated by the analysis of the thermally breakdown products. In case of wood combustion, in addition to the well-known markers at m/z ratios of 60 and 73, two new characteristic masses (m/z 70 and 98) have been revealed as potentially linked to biomass burning. All four masses were also the dominant signals in an ambient sample taken in winter time in Ispra, Italy, confirming the finding that wood burning for residential heating is a major source for particulate matter (PM) in winter at this location. The summer sample from the same location showed no influence of wood burning, but seems to be dominated by SOA, which was confirmed from the comparison with chamber experiment samples. The experiments conducted with terpenes as precursors showed characteristic masses at m/z 58 and 82, which were not observable in any other emission samples and could serve as marker for SOA from terpenes.

Attosecond Ionization Time Delay Around a Shape Resonance in Nitrogen Measured by the RABBIT-2ω method

2021 ◽  
Author(s):  
V. Loriot ◽  
A. Marciniak ◽  
S. Nandi ◽  
G. Karras ◽  
M. Herve ◽  
...  
Keyword(s):  
Time Delay ◽  
Shape Resonance ◽  
Ionization Time
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