scholarly journals Laser-Induced Fluorescence of Hydroxyl (OH) Radical in Cold Atmospheric Discharges

2018 ◽  
Author(s):  
Jan Voráč ◽  
Pavel Dvořák ◽  
Martina Mrkvičková
Keyword(s):  
Laser Induced Fluorescence ◽  
Oh Radical ◽  
Atmospheric Discharges

In situ measurement for tropospheric OH radical by Laser Induced Fluorescence technique during STORM campaign

2020 ◽  
Author(s):  
Fengyang Wang ◽  
Renzhi Hu ◽  
Pinhua Xie ◽  
Yihui Wang ◽  
Shengrong Lou ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Photon Counting ◽  
Ambient Air ◽  
Laser Induced Fluorescence ◽  
Detection Sensitivity ◽  
Oh Radical ◽  
Fluorescence Technique ◽  
Radical Concentration ◽  
Mobile Observation

<p>Hydroxyl (OH) play an essential role in atmospheric chemistry. OH radical is an indicator of atmospheric oxidation and self-purification, which determines the removal of most trace gases in the atmosphere, such as CO, SO<sub>2</sub>, NO<sub>2</sub>, CH<sub>4</sub> and other volatile organic compounds (VOCs). A ground-based system for measurement of tropospheric OH radical by Laser Induced Fluorescence technique (AIOFM-LIF) was developed and integrated into a mobile observation platform for field observation. Ambient air expands through a 0.4 mm nozzle to low pressure. OH radical is irradiated by the 308 nm laser pulse at a repetition rate of 8.5 kHz, accompanying the release fluorescence of the A<sup>2</sup>Σ<sup>+</sup>(v’=0)—X<sup>2</sup>Π<sub>i</sub>(v’’=0) transition at 308 nm with the resultant fluorescence being detected by gated photon counting. The detection sensitivity of AIOFM-LIF system was calibrated by a portable standard OH radical source based on water photolysis-ozone actinometry. Following laboratory and field calibrations to characterise the instrument sensitivity, OH radical detection limits were (1.84±0.26) × 10<sup>5</sup> cm<sup>-3</sup> and (3.69±0.52) × 10<sup>5</sup> cm<sup>-3</sup> at night and noon, respectively. During “A comprehensive STudy of the Ozone foRmation Mechanism in Shenzhen” (STORM) campaign, AIOFM-LIF system was deployed in Shenzhen, China, and OH radical concentration was obtained validly except for the rainy days. Mean diurnal variation of HOx radical concentration was obtained, and the peak was 6.6×10<sup>6</sup> cm<sup>-3</sup> which appeared around 12:00 at noon. A general good agreement of OH radical concentration with j(O<sup>1</sup>D) was observed with a high correlation (R<sup>2</sup> =0.77), which illustrates that photolysis of ozone is an important source of OH radical during this campaign. A box model was applied to simulate the concentrations of OH at this field site, the primary production of OH radical was generally dominated by photolysis of O<sub>3</sub>, HONO, HCHO, while the other production was contributed by calculated species (OVOCs).</p>

Laser-induced fluorescence detection of hydroxyl (OH) radical by femtosecond excitation

2011 ◽  
Vol 36 (10) ◽  
pp. 1776 ◽  
Author(s):  
Hans U. Stauffer ◽  
Waruna D. Kulatilaka ◽  
James R. Gord ◽  
Sukesh Roy
Keyword(s):  
Fluorescence Detection ◽  
Laser Induced Fluorescence ◽  
Oh Radical ◽  
Laser Induced Fluorescence Detection

scholarly journals Development of a Laser-Photofragmentation Laser-Induced Fluorescence instrument for the detection of nitrous acid and hydroxyl radicals in the atmosphere

2021 ◽  
Author(s):  
Brandon Bottorff ◽  
Emily Reidy ◽  
Levi Mielke ◽  
Sebastien Dusanter ◽  
Philip Stevens
Keyword(s):  
Hydroxyl Radicals ◽  
Nitrous Acid ◽  
Laser Induced Fluorescence ◽  
Urban Setting ◽  
Integration Time ◽  
Oh Radical ◽  
Fragmentation Efficiency ◽  
Expansion Technique ◽  
New Instrument ◽  
Radical Fragment

Abstract. A new instrument for the measurement of atmospheric nitrous acid (HONO) and hydroxyl radicals (OH) has been developed using laser photofragmentation (LP) of HONO at 355 nm after expansion into a low-pressure cell, followed by resonant laser-induced fluorescence (LIF) of the resulting OH radical fragment at 308 nm similar to the fluorescence assay by gas expansion technique (FAGE). The LP/LIF instrument is calibrated by determining the photo-fragmentation efficiency of HONO. In this method, a known concentration of OH from the photo-dissociation of water vapor is titrated with nitric oxide to produce a known concentration of HONO. Measurement of the concentration of the OH radical fragment relative to the concentration of HONO provides a measurement of the photo-fragmentation efficiency. The LP/LIF instrument has demonstrated a 1σ detection limit of 9 ppt for a 10-min integration time. Ambient measurements of HONO and OH from a forested environment and an urban setting are presented along with indoor measurements to demonstrate the performance of the instrument.

scholarly journals Development of a laser-photofragmentation laser-induced fluorescence instrument for the detection of nitrous acid and hydroxyl radicals in the atmosphere

2021 ◽  
Vol 14 (9) ◽  
pp. 6039-6056
Author(s):  
Brandon Bottorff ◽  
Emily Reidy ◽  
Levi Mielke ◽  
Sebastien Dusanter ◽  
Philip S. Stevens
Keyword(s):  
Hydroxyl Radicals ◽  
Nitrous Acid ◽  
Laser Induced Fluorescence ◽  
Urban Setting ◽  
Integration Time ◽  
Oh Radical ◽  
Expansion Technique ◽  
New Instrument ◽  
Gas Expansion ◽  
Radical Fragment

Abstract. A new instrument for the measurement of atmospheric nitrous acid (HONO) and hydroxyl radicals (OH) has been developed using laser photofragmentation (LP) of HONO at 355 nm after expansion into a low-pressure cell, followed by resonant laser-induced fluorescence (LIF) of the resulting OH radical fragment at 308 nm similar to the fluorescence assay by gas expansion technique (FAGE). The LP/LIF instrument is calibrated by determining the photofragmentation efficiency of HONO and calibrating the instrument sensitivity for detection of the OH fragment. In this method, a known concentration of OH from the photo-dissociation of water vapor is titrated with nitric oxide to produce a known concentration of HONO. Measurement of the concentration of the OH radical fragment relative to the concentration of HONO provides a measurement of the photofragmentation efficiency. The LP/LIF instrument has demonstrated a 1σ detection limit for HONO of 9 ppt for a 10 min integration time. Ambient measurements of HONO and OH from a forested environment and an urban setting are presented along with indoor measurements to demonstrate the performance of the instrument.

scholarly journals Background-Free Species Detection in Sooty Flames Using Degenerate Four-Wave Mixing

1993 ◽  
Vol 47 (10) ◽  
pp. 1620-1622 ◽  
Author(s):  
S. Kröll ◽  
C. Löfström ◽  
M. Aldén
Keyword(s):  
Background Radiation ◽  
Four Wave Mixing ◽  
Laser Induced Fluorescence ◽  
Oh Radical ◽  
Wave Mixing ◽  
Background Signal ◽  
Species Detection ◽  
Radical Detection ◽  
Degenerate Four Wave Mixing ◽  
Oxygen Flame

The background radiation disturbance in luminous environments has been compared for degenerate four-wave mixing (DFWM) and laser-induced fluorescence (LIF) for OH radical detection in a sooty propane/oxygen flame. The LIF signal generally was considerably stronger than the DFWM signal, but in strongly sooty environments the LIF signal was accompanied by a significant background signal, while the DFWM signal was background-free under all soot loads tested.

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