Spectral Intensity and Lineshape Measurements in the First Overtone Band of HF Using Tunable Diode Lasers

Chou, S.I.; Baer, Douglas S.; Hanson, Ronald K.

doi:10.1006/jmsp.1999.7805

Cited by 27 publications

(7 citation statements)

References 41 publications

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“…Figure 1a shows a stick representation of the absorption maximum of each HF transition in the fundamental and first overtone ro-vibrational bands as calculated from the HITRAN 2012 database [33,34,[37][38][39][40][41] branch. The HF fundamental R(1) peak has a calculated peak absorption of 2.1 × 10 −2 ppm −1 m −1 at 1 atm and 296 K, which is high relative to most molecular species [42].…”

Section: Introductionmentioning

confidence: 99%

Sensing of gaseous HF at low part-per-trillion levels using a tunable 2.5-µm diode laser spectrometer operating at ambient pressure

et al. 2015

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13]. Methods to measure ambient concentrations of gaseous HF are important for regulatory enforcement and monitoring, worker safety and health, and atmospheric research applications. For hazard identification, methods need to detect HF far below dangerous levels and work in real time to allow source identification and to provide evacuation warnings, if necessary [7]. Worker exposure to industrial HF can lead to respiratory and musculoskeletal problems [8,14], and in the USA, the National Institute for Occupational Safety and Health (NIOSH) limits exposure to 6 parts-per-million by volume (ppm) for short-term exposure and 3 ppm averaged over an 8-h workday [15]. Aside from the human toxicity, HF is a highly corrosive gas that can attack metals, glasses, and plastics with deleterious effect.Atmospheric researchers, using the sun as a back-light, have measured total HF concentrations in the upper atmosphere using Fourier transform infrared (FTIR) techniques [1]. These measurements necessarily measure the total integrated concentration from the upper atmosphere to the detector, using models to estimate the distribution of HF as a function of height [16]. It is highly desirable to supplement these path-integrated measurements with sensitive point measurements using tunable diode laser absorption spectroscopy (TDLAS) or FTIR spectrometers to validate the models [10,17]. For atmospheric research, these sensors must also be compact and lightweight and have sufficiently low power consumption suitable for weather balloons [17,18] or aircraft [19] instrument packages. Ideally, they should operate at sufficiently high acquisition speeds to allow detection of small changes in background concentrations on time scales of a few seconds. In the stratosphere, HF is long-lived and measured concentrations are 0.5-0.6 parts-per-billion by volume (ppb) [20], depending on altitude, latitude, and season. Closer to the ground, rain Abstract We demonstrate a sensor based on tunable diode laser absorption spectroscopy for the detection of hydrogen fluoride (HF) gas at ambient pressure. Absorption from the HF R(1) ro-vibrational peak at ν̃ = 4038.962 cm −1 (2.476 µm) in the fundamental (Δν = 1) band is measured. A quantitative spectral fit based on HITRAN data is used to account for overlapping spectral peaks of HF and water vapor, with an rms residual noise of 5 × 10 −4 absorbance units. The sensor is optimized for the detection of transient variations in HF concentration. We measure noise-equivalent concentrations for HF of 38 parts-per-trillion by volume (ppt) for 1-s integration times and 2.3 ppt for 10-min integration times.

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Section: Introductionmentioning

confidence: 99%

Sensing of gaseous HF at low part-per-trillion levels using a tunable 2.5-µm diode laser spectrometer operating at ambient pressure

et al. 2015

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“…This result is in agreement with the work of Hanson and co-workers which indicates that under our experimental conditions, pressure broadening effects should not be present. 22,23 The peak gain shown in Figure 5 is 0.11 % cm -1 and the peak width (FWHM) is 565 MHz. The temperature, extracted using the spectral width, is determined to be 239 K. This is in reasonable agreement with the results of Carroll, et al 24 who used Rigrod theory 25 and extensive modeling to determine the small signal gain for a similar HF laser device.…”

Section: Small Signal Gain Measurementsmentioning

confidence: 98%

Hydrogen fluoride overtone laser: experimental methods of characterization

Wisniewski

Hewett

Manke

et al. 2004

High-Power Laser Ablation V

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The uncertainty in both the fluorine atom concentration and the gain length has inhibited the development of accurate and device independent models of HF overtone lasers. Furthermore, previous methods of measuring the small signal gain were cumbersome and could not easily generate spatial maps of the gain in the cavity. Experimental techniques have been developed to directly measure the concentration of fluorine atoms, the gain length and the small signal gain in a hydrogen fluoride 5 cm slit nozzle laser. A gas phase titration technique was utilized to measure the fluorine atom concentration using HCl as the titrant. The gain length was measured using a pitot probe to locate the interface of the primary flow with the high Mach number shroud flows. A tunable diode laser was utilized to perform small signal gain measurements on HF overtone (v=2 0) transitions.

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“…How ever, it has been well known for more than 40 years that the actual profile of an individual (isolated) line near its center noticeably differs from the Voigt one. Thus, despite the well isolated position, HF rotational and vibrational lines show a noticeable deviation from the Voigt profile, namely, abnormal asymmetry and, in certain cases, collisional narrowing [19,20]. More intricate spectroscopic models have been used in mea surements of collisional broadening of lines only in the past 10-15 years; among them, Galatry [21] and Rau tian-Sobelman profiles [22], which take into account the Dicke effect [23] of decreasing Doppler broaden ing due to collisional limitations of the free movement of active (absorbing) molecules.…”

Section: Introductionmentioning

confidence: 93%

Near IR TDLS study of HF first overtone line shape. I. Experimental results

2012

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The HF first overtone vibration rotational absorption spectral line profile (the transition 0-2 R(0)) broadened by Ar (mixture HF : Ar = 1 : 150, T = 295 K, P = 10-300 mm Hg) is studied by the method of near IR diode laser spectroscopy. A tunable distributed feedback fiber diode laser was used as a radiation source in a two channel spectrometer (λ ∼ 1.284 μm, spectral tuning range Δν = 1.5-2.0 cm -1 , the output radiation power is 15 mW, the spectral half width of lasing lines is ∼ 5 MHz). The broadening and shifting coefficients of the considered HF line are determined, using traditional Voigt, Rautian, and Galatry spectral profiles.

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Spectral Intensity and Lineshape Measurements in the First Overtone Band of HF Using Tunable Diode Lasers

Cited by 27 publications

References 41 publications

Sensing of gaseous HF at low part-per-trillion levels using a tunable 2.5-µm diode laser spectrometer operating at ambient pressure

Sensing of gaseous HF at low part-per-trillion levels using a tunable 2.5-µm diode laser spectrometer operating at ambient pressure

Hydrogen fluoride overtone laser: experimental methods of characterization

Near IR TDLS study of HF first overtone line shape. I. Experimental results

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