Trace Detection of Nitrocompounds by ArF Laser Photofragmentation/Ionization Spectrometry

1993 ◽  
Vol 47 (11) ◽  
pp. 1907-1912 ◽  
Author(s):  
Josef B. Simeonsson ◽  
George W. Lemire ◽  
Rosario C. Sausa
Keyword(s):  
Ground State ◽  
Multiphoton Ionization ◽  
Ionization Mass ◽  
Trace Detection ◽  
Atmospheric Conditions ◽  
Experimental Conditions ◽  
Detection Range ◽  
Arf Laser ◽  
Free Environment ◽  
193 Nm

A new method for detecting trace vapors of NO2-containing compounds near atmospheric conditions has been demonstrated with the use of one-color-laser photofragmentation/ionization spectrometry. An ArF laser is employed to both photolytically fragment the target molecules in a collision-free environment and ionize the characteristic NO fragments. The production of NO is hypothesized to result from a combination of two NO2 unimolecular fragmentation pathways, one yielding NO in its X2II electronic ground state and the other in its A2Σ+ excited state. Ionization of ground-state NO molecules is accomplished by resonance-enhanced multiphoton ionization processes via its A2Σ+ ← X2II (3, 0), B2II ← X2II (7, 0) and/or D2Σ+ ← X2II (0, 1) bands at 193 nm. The analytical utility of this method is demonstrated in a molecular beam time-of-flight apparatus. Limits of detection range from the parts-per-million (ppm) to parts-per-billion (ppb) level for NO, NO2, CH3NO2, dimethylnitramine (DMNA), ortho- and meta-nitrotoluene, nitrobenzene, and trinitrotoluene (TNT). Under effusive beam experimental conditions, discrimination between structural isomers, ortho-nitrotoluene and meta-nitrotoluene, has been demonstrated with the use of their characteristic photofragmentation/ionization mass spectra.

Amplification of fibre Bragg grating reflectivity by post-writing exposure with a 193 nm ArF laser

1994 ◽  
Vol 30 (14) ◽  
pp. 1133-1134 ◽  
Author(s):  
P. E. Dyer ◽  
K. C. Byron ◽  
R. J. Farley ◽  
R. Giedl
Keyword(s):  
Bragg Grating ◽  
Fibre Bragg Grating ◽  
Arf Laser ◽  
193 Nm

Ultraviolet photodissociation dynamics of PCl3 at 235 nm: three-dimensional ion imaging and theoretical analysis

2021 ◽  
Author(s):  
Alexei Chichinin ◽  
Christof Maul ◽  
Karl-Heinz Gericke
Keyword(s):  
Theoretical Analysis ◽  
Ground State ◽  
Multiphoton Ionization ◽  
Three Dimensional ◽  
Ion Imaging ◽  
Ultraviolet Photodissociation

The photodissociation dynamics of PCl3 at 235 nm has been studied by monitoring ground state Cl(2P3/2) and spin-orbitally excited Cl(2P1/2) atoms by resonance enhanced multiphoton ionization(REMPI). Also, the PCl+n (n=0,1,2)...

Resonant Multiphoton Ionization ofH2by an ArF Laser and Application to Atmospheric Molecules

1996 ◽  
Vol 35 (Part 1, No. 5A) ◽  
pp. 2672-2676 ◽  
Author(s):  
Mitsuo Maeda ◽  
Tatsuo Okada ◽  
Yasuyuki Hirakawa ◽  
Michihiro Uchiumi ◽  
Katsunori Muraoka
Keyword(s):  
Multiphoton Ionization ◽  
Atmospheric Molecules ◽  
Arf Laser

scholarly journals Temperature uniformity in the CERN CLOUD chamber

2017 ◽  
Vol 10 (12) ◽  
pp. 5075-5088 ◽  
Author(s):  
António Dias ◽  
Sebastian Ehrhart ◽  
Alexander Vogel ◽  
Christina Williamson ◽  
João Almeida ◽  
...  
Keyword(s):  
Steady State ◽  
Air Temperature ◽  
Elevated Temperatures ◽  
Trace Gases ◽  
Vertical Direction ◽  
Cloud Chamber ◽  
Temperature Uniformity ◽  
Atmospheric Conditions ◽  
Cloud Droplets ◽  
Experimental Conditions

Abstract. The CLOUD (Cosmics Leaving OUtdoor Droplets) experiment at CERN (European Council for Nuclear Research) investigates the nucleation and growth of aerosol particles under atmospheric conditions and their activation into cloud droplets. A key feature of the CLOUD experiment is precise control of the experimental parameters. Temperature uniformity and stability in the chamber are important since many of the processes under study are sensitive to temperature and also to contaminants that can be released from the stainless steel walls by upward temperature fluctuations. The air enclosed within the 26 m3 CLOUD chamber is equipped with several arrays (strings) of high precision, fast-response thermometers to measure its temperature. Here we present a study of the air temperature uniformity inside the CLOUD chamber under various experimental conditions. Measurements were performed under calibration conditions and run conditions, which are distinguished by the flow rate of fresh air and trace gases entering the chamber at 20 and up to 210 L min−1, respectively. During steady-state calibration runs between −70 and +20 °C, the air temperature uniformity is better than ±0.06 °C in the radial direction and ±0.1 °C in the vertical direction. Larger non-uniformities are present during experimental runs, depending on the temperature control of the make-up air and trace gases (since some trace gases require elevated temperatures until injection into the chamber). The temperature stability is ±0.04 °C over periods of several hours during either calibration or steady-state run conditions. During rapid adiabatic expansions to activate cloud droplets and ice particles, the chamber walls are up to 10 °C warmer than the enclosed air. This results in temperature differences of ±1.5 °C in the vertical direction and ±1 °C in the horizontal direction, while the air returns to its equilibrium temperature with a time constant of about 200 s.

Multiphoton Ionization Mass Spectroscopy of Fullerenes in Methane Diffusion Flames

1994 ◽  
Vol 359 ◽  
Author(s):  
H. Hepp ◽  
K. Siegmann ◽  
K. Sattler
Keyword(s):  
Aromatic Hydrocarbons ◽  
Atmospheric Pressure ◽  
Diffusion Flames ◽  
Multiphoton Ionization ◽  
Ionization Mass ◽  
Ionization Time ◽  
Ionization Mass Spectroscopy ◽  
Polycyclic Aromatic ◽  
On Line ◽  
Methane Diffusion

ABSTRACTMultiphoton ionization time-of-flight mass spectrosocopy is used as an on-line technique to investigate polycyclic aromatic hydrocarbons (PAH) and fullerenes in atmospheric pressure flames. We have recorded height profiles of neutral PAH and fullerenes in methane/argon diffusion flames. Fullerenes ranging from C32 to at least C150 are found in a region where PAH concentration starts to decrease. Uniformity of the profiles indicates that the fullerenes do not grow from smaller to larger ones. The influence of the amount of argon additive is discussed.

scholarly journals Laboratory study on new particle formation from the reaction OH + SO<sub>2</sub>: influence of experimental conditions, H<sub>2</sub>O vapour, NH<sub>3</sub> and the amine tert-butylamine on the overall process

2010 ◽  
Vol 10 (3) ◽  
pp. 6447-6484 ◽  
Author(s):  
T. Berndt ◽  
F. Stratmann ◽  
M. Sipilä ◽  
J. Vanhanen ◽  
T. Petäjä ◽  
...  
Keyword(s):  
Relative Humidity ◽  
High Sensitivity ◽  
Particle Growth ◽  
Counting Efficiency ◽  
Oh Radicals ◽  
Atmospheric Conditions ◽  
Promoting Effect ◽  
Experimental Conditions ◽  
H2so4 Concentration ◽  
Tert Butylamine

Abstract. Nucleation experiments starting from the reaction of OH radicals with SO2 have been performed in the IfT-LFT flow tube under atmospheric conditions at 293±0.5 K for a relative humidity of 13–61%. The presence of different additives (H2, CO, 1,3,5-trimethylbenzene) for adjusting the OH radical concentration and resulting OH levels in the range (4–300)·105 molecule cm−3 did not influence the nucleation process itself. The number of detected particles as well as the threshold H2SO4 concentration needed for nucleation was found to be strongly dependent on the counting efficiency of the used counting devices. High-sensitivity particle counters allowed the measurement of freshly nucleated particles with diameters down to about 1.5 nm. A parameterization of the experimental data was developed using power law equations for H2SO4 and H2O vapour. The exponent for H2SO4 from different measurement series was in the range of 1.7–2.1 being in good agreement with those arising from analysis of nucleation events in the atmosphere. For increasing relative humidity, an increase of the particle number was observed. The exponent for H2O vapour was found to be 3.1 representing a first estimate. Addition of 1.2·1011 molecule cm−3 or 1.2·1012 molecule cm−3 of NH3 (range of atmospheric NH3 peak concentrations) revealed that NH3 has a measureable, promoting effect on the nucleation rate under these conditions. The promoting effect was found to be more pronounced for relatively dry conditions. NH3 showed a contribution to particle growth. Adding the amine tert-butylamine instead of NH3, the enhancing impact for nucleation and particle growth appears to be stronger.

scholarly journals Formaldehyde and Glyoxal Measurement Deploying a Selected Ion Flow Tube Mass Spectrometer (SIFT-MS)

2021 ◽  
Author(s):  
Antonia Zogka ◽  
Manolis N. Romanias ◽  
Frederic Thevenet
Keyword(s):  
Proton Transfer ◽  
Real Time ◽  
Mass Spectrometer ◽  
Sharp Decrease ◽  
Ionization Mass ◽  
Flow Tube ◽  
Experimental Conditions ◽  
Ion Flow ◽  
Outdoor Environments ◽  
Selected Ion Flow Tube

Abstract. Formaldehyde (FM) and glyoxal (GL) are important atmospheric species of indoor and outdoor environments. They are either directly emitted in the atmosphere or they are formed through the oxidation of organic compounds by indoor and/or outdoor atmospheric oxidants. Despite their importance, the real-time monitoring of these compounds with soft ionization mass spectrometric techniques, e.g. proton transfer mass spectrometry (PTR-MS), remains problematic and is accompanied by low sensitivity. In this study, we evaluate the performance of a multi-ion selected ion flow tube mass spectrometer (SIFT-MS) to monitor in real-time atmospherically relevant concentrations of FM and GL under controlled experimental conditions. The SIFT-MS used is operated under standard conditions (SC), as proposed by the supplier, and customized conditions (CC), to achieve higher sensitivity. In the case of FM, SIFT-MS sensitivity is marginally impacted by RH, and the detection limits achieved are below 200 ppt. Contrariwise, in the case of GL, a sharp decrease of instrument sensitivity is observed with increasing RH when the H3O+ ion is used. Nevertheless, the detection of GL using NO+ precursor ion is moderately impacted by moisture with an actual positive sensitivity response. Therefore, we recommend the use of NO+ precursor for reliable detection and quantitation of GL. This work evidences that SIFT-MS can be considered as an efficient tool to monitor the concentration of FM and GL using SIFT-MS in laboratory experiments and potentially in indoor or outdoor environments. Furthermore, SIFT-MS technology still allows great possibilities for sensitivity improvement and high potential for monitoring low proton transfer affinity compounds.

scholarly journals Laser filament-induced aerosol formation

2013 ◽  
Vol 13 (9) ◽  
pp. 4593-4604 ◽  
Author(s):  
H. Saathoff ◽  
S. Henin ◽  
K. Stelmaszczyk ◽  
M. Petrarca ◽  
R. Delagrange ◽  
...  
Keyword(s):  
Particle Production ◽  
Ambient Air ◽  
Particle Formation ◽  
Oxygen Mixture ◽  
Atmospheric Conditions ◽  
Aerosol Formation ◽  
Experimental Conditions ◽  
Particle Yield ◽  
The Given ◽  
Terawatt Laser

Abstract. Using the aerosol and cloud simulation chamber AIDA, we investigated the laser filament induced particle formation in ambient air, humid synthetic air, humid nitrogen, argon–oxygen mixture, and pure argon in order to simulate the particle formation under realistic atmospheric conditions as well as to investigate the influence of typical gas-phase atmospheric constituents on the particle formation. Terawatt laser plasma filaments generated new particles in the size range 3 to 130 nm with particle production rates ranging from 1 × 107 to 5 × 109 cm−3 plasma s−1 for the given experimental conditions. In all cases the particle formation rates increased exponentially with the water content of the gas mixture. Furthermore, the presence of a few ppb of trace gases like SO2 and α-pinene clearly enhanced the particle yield by number, the latter also by mass. Our findings suggest that new particle formation is efficiently supported by oxidized species like acids generated by the photoionization of both major and minor components of the air, including N2, NH3, SO2 and organics.

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