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A Campargue - One of the best experts on this subject based on the ideXlab platform.
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sub mhz accuracy measurement of the s 2 2 0 transition frequency of d2 by comb assisted cavity ring down spectroscopy
2016Co-Authors: D Mondelain, S Kassi, Tommaso Sala, D Romanini, Davide Gatti, A CampargueAbstract:Abstract The line position of the very weak S(2) transition of deuterium in the 2–0 band has been measured with a Comb-Assisted Cavity Ring Down spectrometer. The high sensitivity spectra were recorded at 5 and 10 mbar with a Noise Equivalent Absorption, α min , of 8 × 10 –11 cm −1 . The line positions at 5 and 10 mbar were measured with sub-MHz accuracy (460 and 260 kHz, respectively). After correction of the line Pressure-Shift, the frequency at zero Pressure of the S(2) transition of the first overtone band was determined to be 187 104 299.51 ± 0.50 MHz. This value agrees within 1.7 MHz with the frequency obtained from the best available ab initio calculations and corresponds to only 15% of the claimed theoretical uncertainty.
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broadband and highly sensitive comb assisted cavity ring down spectroscopy of co near 1 57µm with sub mhz frequency accuracy
2015Co-Authors: D Mondelain, S Kassi, Tommaso Sala, D Romanini, A Campargue, M MarangoniAbstract:Abstract A self-referenced frequency comb has been combined with a cavity ring down (CRD) spectrometer to achieve a sub-MHz accuracy on the derived positions of the absorption lines. The frequency emitted by the distributed feedback (DFB) laser diode used in the spectrometer was obtained from the frequency of its beat note with the closest mode of the frequency comb. This delivers excellent frequency accuracy over a broad spectral region with sensitivity (noise equivalent absorption) of 1×10–11 cm−1 Hz−1/2. This setup is used to measure the absorption spectrum of CO over a wide range corresponding to the 3–0 band (6172.5–6418.0 cm−1). Accurate values of line centers are measured for a total of 184 lines of four CO isotopologues, namely 12C16O, 13C16O, 12C18O and 12C17O present in “natural” abundances in our sample. The measurements include the first extensive study of the 3–0 band of 12C18O and 12C17O, of the 4–1 hot band of 12C16O and the detection of new high-J transitions of the 3–0 band of 12C16O up to J=34. The line centers were corrected for the self-Pressure Shift and used to derive the upper state spectroscopic parameters. The obtained standard deviation of about 300 kHz and 500 kHz for the 3–0 band of 12C16O and of the minor isotopologues, respectively, is a good estimate of the average accuracy of the reported line centers. The resulting 3–0 line list of 12C16O provided as Supplementary material includes 69 reference line positions with a 300 kHz accuracy for the 6183–6418 cm−1 region.
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the absorption spectrum of d2 ultrasensitive cavity ring down spectroscopy of the 2 0 band near 1 7 μm and accurate ab initio line list up to 24 000 cm 1
2012Co-Authors: S Kassi, A Campargue, Krzysztof Pachucki, Jacek KomasaAbstract:Eleven very weak electric quadrupole transitions Q(2), Q(1), S(0)-S(8) of the first overtone band of D2 have been measured by very high sensitivity CW-cavity ring down spectroscopy (CRDS) between 5850 and 6720 cm−1. The noise equivalent absorption of the recordings is on the order of αmin ≈ 3 × 10−11 cm−1. By averaging a high number of spectra, the noise level was lowered to αmin ≈ 4 × 10−12 cm−1 in order to detect the S(8) transition which is among the weakest transitions ever detected in laboratory experiments (line intensity on the order of 1.8 × 10−31 cm/molecule at 296 K). A Galatry profile was used to reproduce the measured line shape and derive the line strengths. The Pressure Shift and position at zero Pressure limit were determined from recordings with Pressures ranging between 10 and 750 Torr. A highly accurate theoretical line list was constructed for pure D2 at 296 K. The intensity threshold was fixed to a value of 1 × 10−34 cm/molecule at 296 K. The obtained line list is provided as supplemen...
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the absorption spectrum of h2 crds measurements of the 2 0 band review of the literature data and accurate ab initio line list up to 35 000 cm 1
2012Co-Authors: A Campargue, S Kassi, Krzysztof Pachucki, Jacek KomasaAbstract:Five very weak transitions—O(2), O(3), O(4), O(5) and Q(5)—of the first overtone band of H2 are measured by very high sensitivity CW-Cavity Ring Down Spectroscopy (CRDS) between 6900 and 7920 cm−1. The noise equivalent absorption of the recordings is on the order of αmin ≈ 5 × 10−11 cm−1 allowing for the detection of the O(5) transition with an intensity of 1.1 × 10−30 cm per molecule, the smallest intensity value measured so far for an H2 absorption line. A Galatry profile was used to reproduce the measured line shape and derive the line strengths. The Pressure Shift of the O(2) and O(3) lines was accurately determined from a series of recordings with Pressure ranging between 10 and 700 Torr. From an exhaustive review of the literature data, the list of H2 absorption lines detected so far has been constructed. It includes a total of 39 transitions ranging from the S(0) pure rotational line near 354 cm−1 up to the S(1) transition of the (5-0) band near 18908 cm−1. These experimental values are compared to a highly accurate theoretical line list constructed for pure H2 at 296 K (0–35000 cm−1, intensity cut off of 1 × 10−34 cm per molecule). The energy levels and transition moments were computed from high level quantum mechanics calculations. The overall agreement between the theoretical and experimental values is found to be very good for the line positions. Some deviations for the intensities of the high overtone bands (V > 2) are discussed in relation with possible Pressure effects affecting the retrieved intensity values. We conclude that the hydrogen molecule is probably a unique case in rovibrational spectroscopy for which first principles theory can provide accurate spectroscopic parameters at the level of the performances of the state of the art experimental techniques.
D A Ritchie - One of the best experts on this subject based on the ideXlab platform.
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high resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser
2006Co-Authors: Heinzwilhelm Hubers, S G Pavlov, Heiko Richter, A Semenov, L Mahler, Alessandro Tredicucci, Harvey E Beere, D A RitchieAbstract:The quantum cascade laser is a powerful, narrow linewidth, and continuous wave source of terahertz radiation. The authors have implemented a distributed feedback device in a spectrometer for high-resolution gas phase spectroscopy. Amplitude as well as frequency modulation schemes have been realized. The absolute frequency was determined by mixing the radiation from the quantum cascade laser with that from a gas laser. The Pressure broadening and the Pressure Shift of a rotational transition of methanol at 2.519THz were measured in order to demonstrate the performance of the spectrometer.The quantum cascade laser is a powerful, narrow linewidth, and continuous wave source of terahertz radiation. The authors have implemented a distributed feedback device in a spectrometer for high-resolution gas phase spectroscopy. Amplitude as well as frequency modulation schemes have been realized. The absolute frequency was determined by mixing the radiation from the quantum cascade laser with that from a gas laser. The Pressure broadening and the Pressure Shift of a rotational transition of methanol at 2.519THz were measured in order to demonstrate the performance of the spectrometer.
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high resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser
2006Co-Authors: Heinzwilhelm Hubers, S G Pavlov, Heiko Richter, A Semenov, L Mahler, Alessandro Tredicucci, Harvey E Beere, D A RitchieAbstract:The quantum cascade laser is a powerful, narrow linewidth, and continuous wave source of terahertz radiation. The authors have implemented a distributed feedback device in a spectrometer for high-resolution gas phase spectroscopy. Amplitude as well as frequency modulation schemes have been realized. The absolute frequency was determined by mixing the radiation from the quantum cascade laser with that from a gas laser. The Pressure broadening and the Pressure Shift of a rotational transition of methanol at 2.519THz were measured in order to demonstrate the performance of the spectrometer.
P D Sanz - One of the best experts on this subject based on the ideXlab platform.
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Pressure Shift nucleation a potential tool for freeze concentration of fluid foods
2012Co-Authors: Laura Otero, Pascual Sanz, Berengere Guignon, P D SanzAbstract:Abstract Pressure-Shift nucleation (PSN) has been evaluated as a potential substitute of the crystallization step at the scraped surface heat exchanger in conventional freeze concentration. To do that, PSN experiments were carried out at different Pressure and temperature conditions in orange juices of several concentrations. After crystallization, the final concentration reached and the size and shape of the ice crystals formed were measured. The results obtained showed that the higher the Pressure and the lower the temperature employed in the PSN experiments, the higher is the final concentration in the juice and the smaller the ice crystals formed. Four important advantages of Pressure-Shift nucleation over conventional crystallization were found: temperature in the Pressure vessel can be relatively high if Pressure is increased enough, the desired concentration can be achieved in the whole sample quasi-instantaneously just after expansion, ice crystals produced are round in shape without pockets and indentations and they are homogeneously distributed throughout the sample. Industrial relevance Freeze concentration is the most advantageous technique to obtain high quality food concentrates without appreciable loss in taste, aroma, color, or nutritive value. However, it is hardly employed in the food industry mainly due to economic aspects of the technology. In the last decades, many efforts have been made to improve the crystallization phase, the most expensive step in freeze concentration, without definitive success. The results obtained in this paper show that Pressure-Shift nucleation presents a number of advantages over the traditional crystallization step at the scraped surface heat exchanger which can be exploited to improve the industrial freeze concentration process.
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high Pressure Shift freezing versus high Pressure assisted freezing effects on the microstructure of a food model
2006Co-Authors: P Fernandez, Laura Otero, Berengere Guignon, P D SanzAbstract:Abstract Gelatin gel samples (10% gelatin, w/w) were frozen by high-Pressure Shift freezing (HPSF) and by high-Pressure assisted freezing (HPAF) with the phase transition at identical Pressure conditions (0.1, 50, and 100 MPa) so as to allow valid comparisons. The corresponding temperature/Pressure profiles were recorded in order to characterize the processes. Also, the ice crystal distributions were analyzed to estimate the effects of both freezing methods on the food microstructure. Results clearly showed that high-Pressure Shift freezing is the more advantageous method. The supercooling attained after the expansion and the consequent instantaneous freezing of water, together with the temperature drop in the Pressure medium, induced short phase transition times (5.9, 8.6, and 13.7 min in HPSF versus 14.8, 14.1, and 23.1 min in HPAF at 0.1, 50, and 100 MPa, respectively) and a homogeneous distribution of small ice crystals throughout the sample.
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assessment of cell damage in high Pressure Shift frozen broccoli comparison with market samples
2006Co-Authors: P Fernandez, Laura Otero, Guadalupe Prestamo, P D SanzAbstract:Pressure-Shift freezing (PSF) is one of the most promising methods for obtaining high-quality frozen products. The aim of this work was to analyse the differences between broccoli that was frozen using two different PSF processes. In one of the processes, all the freezing was done inside the high-Pressure vessel tempered at −20.5 °C. In the other process, the sample was taken out of the vessel after expansion, and freezing was completed using liquid N2. Colour, texture, electrical conductivity, microstructure and drip losses after centrifugation were analysed and a sensory test was performed. The results were compared with those for conventionally frozen broccoli purchased at the market. PSF broccoli presented less cell damage, lower drip losses and better texture than the market samples. The two different PSF processes assayed produced no significant differences in the final quality of the samples.
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high Pressure Shift freezing main factors implied in the phase transition time
2006Co-Authors: Laura Otero, P D SanzAbstract:We have studied the dynamics of the high-Pressure-Shift freezing (HPSF) process and the main parameters implied. Conventional freezing experiments at atmospheric conditions and HPSF experiments were carried out at identical temperatures and different Pressures and the phase transition times compared. Phase transition times in HPSF experiments were lower than their homologues at atmospheric Pressure in all cases. The reduction depends on the Pressure and temperature conditions before expansion. These variables are highly involved in the supercooling reached and govern both the percentage of ice formed during the Pressure release and the temperature drop in the Pressure medium. After expansion, the Pressure medium plays a significant role in the heat removal from the sample. Good predictions of plateau times can be made from initial Pressure and temperature values, both process parameters that can be readily adjusted in the food industry.
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protein denaturation and structural damage during high Pressure Shift freezing of porcine and bovine muscle
2000Co-Authors: F Fernandezmartin, Laura Otero, Maria Teresa Solas, P D SanzAbstract:Pork and beef muscles were subjected to 200 MPa and 20 °C with or without water freezing. Both tissues responded to the treatment with similar behavior. Protein denaturation was greater when freezing occurred. Pressure-induced cold denaturation was complete for actin and very considerable for myosin and other muscle proteins. Connective proteins remained practically unaltered by pressurization and/or freezing. Structural changes in the muscle at sarcomere levels caused by pressurization were more severe when freezing occurred. Color, drip loss, and textural properties on the pressurized samples also revealed an additional deleterious influence of freezing.
Malathy V Devi - One of the best experts on this subject based on the ideXlab platform.
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line parameters for co2 and self broadening in the ν1 band of hd16o
2017Co-Authors: Malathy V Devi, Chris D Benner, Keeyoon Sung, Timothy J Crawford, Robert R Gamache, Candice L Renaud, Mary Ann H Smith, A W Mantz, Geronimo L VillanuevaAbstract:Abstract Lorentz half-width coefficients and their temperature dependence exponents for CO2 broadening in the fundamental bands of HDO are important for reliable and accurate interpretation of Mars and Venus atmospheric data and to determine D/H. Uncertainties in the temperature dependences of the CO2-broadened half-width coefficients lead to large errors in the retrieved mixing ratios and hence in HDO column abundances. In this high-resolution FTIR laboratory study, we report first measurements of the temperature dependences of half-width coefficients for HDO transitions in the ν1 and 2ν2 bands broadened by CO2. Accurate line positions, intensities, CO2-broadened width and Pressure Shift coefficients, their temperature dependences, collisional line mixing coefficients for HDO-CO2 system and quadratic speed dependence parameters have been retrieved for a large number of transitions in the ν1 band. Room-temperature self-broadened half-width coefficients, self-Shift coefficients, and collisional line-mixing coefficients for HDO-HDO system were also measured for the same number of ν1 transitions. Positions and intensities were measured for nearly 60 transitions in the weaker 2ν2 band along with a few room-temperature measurements of CO2- and self-broadening and Pressure-Shift coefficients. These results were obtained from simultaneous nonlinear least squares fittings of ten high-resolution absorption spectra recorded with the Bruker IFS-125HR FTS at JPL and two coolable sample cells. Modified Complex Robert-Bonamy (MCRB) formalism was applied to compute both types of broadening and Pressure Shift coefficients, and the temperature dependences of the CO2- and self-broadening parameters. Present measurements are compared with the MCRB calculations and other theoretical values reported in the literature.
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line parameters for co2 broadening in the ν2 band of hd16o
2017Co-Authors: Malathy V Devi, Chris D Benner, Keeyoon Sung, Timothy J Crawford, Robert R Gamache, Candice L Renaud, Mary Ann H Smith, A W Mantz, Geronimo L VillanuevaAbstract:Abstract CO 2 -rich planetary atmospheres such as those of Mars and Venus require accurate knowledge of CO 2 broadened HDO half-width coefficients and their temperature dependence exponents for reliable abundance determination. Although a few calculated line lists have recently been published on HDO–CO 2 line shapes and their temperature dependences, laboratory measurements of those parameters are thus far non-existent. In this work, we report the first measurements of CO 2 -broadened half-width and Pressure-Shift coefficients and their temperature dependences for over 220 transitions in the ν 2 band. First measurements of self-broadened half-width and self-Shift coefficients at room temperature are also obtained for majority of these transitions. In addition, the first experimental determination of collisional line mixing has been reported for 11 transition pairs for HDO–CO 2 and HDO–HDO systems. These results were obtained by analyzing ten high-resolution spectra of HDO and HDO–CO 2 mixtures at various sample temperatures and Pressures recorded with the Bruker IFS-125HR Fourier transform spectrometer at the Jet Propulsion Laboratory (JPL). Two coolable absorption cells with path lengths of 20.38 cm and 20.941 m were used to record the spectra. The various line parameters were retrieved by fitting all ten spectra simultaneously using a multispectrum nonlinear least squares fitting algorithm. The HDO transitions in the 1100–4100 cm −1 range were extracted from the HITRAN2012 database. For the ν 2 and 2ν 2 -ν 2 bands there were 2245 and 435 transitions, respectively. Modified Complex Robert–Bonamy formalism (MCRB) calculations were made for the half-width coefficients, their temperature dependence and the Pressure Shift coefficients for the HDO–CO 2 and HDO–HDO collision systems. MCRB calculations are compared with the measured values.
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spectral line parameters including temperature dependences of air broadening for the 2 0 bands of 13c16o and 12c18o at 2 3 μm
2012Co-Authors: Malathy V Devi, Chris D Benner, Keeyoon Sung, Mary Ann H Smith, A W Mantz, L R BrownAbstract:Abstract The first air broadening line shape parameters were determined for the 2 ← 0 bands of 13 C 16 O near 4166.8 cm −1 and 12 C 18 O near 4159.0 cm −1 . Air-broadened Lorentz half-width coefficients, their temperature dependence exponents; air-induced Pressure Shift coefficients, their temperature dependences; and air line mixing coefficients were measured. Additionally, speed-dependent line shapes with line mixing employing the off-diagonal relaxation matrix element coefficients were applied to minimize the fit residuals. Finally, individual line positions and line intensities of the two isotopologues were constrained to the well-known theoretical quantum mechanical expressions in order to obtain the rovibrational ( G , B , D and H ) and band intensity parameters (including Herman–Wallis coefficients). For this, laboratory spectra were recorded at 0.005 cm −1 resolution using a temperature-controlled coolable absorption cell configured inside a Bruker IFS 125HR Fourier transform spectrometer. Gas temperatures and Pressures for the spectra varied from 150 to 298 K and 20 to 700 Torr, respectively. Results were obtained from broad-band multispectrum least-squares fitting of the 4000–4360 cm −1 spectral region. Four isotope-enriched pure sample spectra and twelve spectra with air + CO samples ( 13 C 16 O or 12 C 18 O, as appropriate) were fitted simultaneously. The results obtained for 13 C 16 O and 12 C 18 O are compared and discussed.
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lorentz half width Pressure induced Shift and speed dependent coefficients in oxygen broadened co2 bands at 6227 and 6348 cm 1 using a constrained multispectrum analysis
2010Co-Authors: Malathy V Devi, Charles E Miller, Chris D Benner, Adriana PredoicrossAbstract:Abstract The McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory (NSO) on Kitt Peak, Arizona, was used to record infrared high resolution absorption spectra of CO 2 spectra broadened by O 2 . These spectra were analyzed to measure O 2 -broadened half-width coefficients, O 2 -induced Pressure-Shift coefficients and speed dependent parameters for transitions in the 30013←00001 and 30012←00001 bands of 16 O 12 C 16 O located near 6227 and 6348 cm −1 , respectively. All spectra were obtained at room temperature using the long path, 6 m base path White cell available at NSO. A multispectrum nonlinear least-squares fitting algorithm employing Voigt line shapes modified to include line mixing and speed dependence was used to fit simultaneously a total of 19 spectra in the 6120–6280 cm −1 (30013←00001) and 6280–6395 cm −1 (30012←00001) spectral regions. 16 of the 19 spectra analyzed in this work were self broadened and three spectra were lean mixtures of CO 2 in O 2 . The volume mixing ratios of CO 2 in the three spectra varied between 0.06 and 0.1. Lorentz half-width and Pressure-induced Shift coefficients were measured for all transitions in the P(50)–R(50) range in both vibrational bands. The results obtained from present analysis have been compared with measurements available in the literature for self-, air-, oxygen- and argon-broadening. No significant differences were observed between the broadening and Shift coefficients of the two bands. The N 2 -broadened half-width and Pressure-Shift coefficients were computed from measured air- and O 2 -broadened width and Shift coefficients.
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temperature dependences for air broadened lorentz half width and Pressure Shift coefficients in the 30013 00001 and 30012 00001 bands of co2 near 1600 nm this article is part of a special issue on spectroscopy at the university of new brunswick in honour of colan linton and ron lees
2009Co-Authors: Predoicrossa A Predoicross, Malathy V Devi, Chris D Benner, A Mckellara R W R W Mckellar, R Gamacher R R Gamache, C Millerc E Miller, R Tothr A A Toth, L Brownl R R BrownAbstract:In this study, 39 high-resolution spectra of pure and air-broadened CO2 recorded at temperatures between 215 and 294 K were analyzed using a multispectrum nonlinear least-squares technique to determine temperature dependences of air-broadened Lorentz half-width and air-induced Pressure Shift coefficients for over 100 individual 12C16O2 transitions in the 30012←00001 (at 6348 cm–1) and 30013←00001 (at 6228 cm–1) bands. Data were recorded with two different Fourier transform spectrometers (Kitt Peak FTS at the National Solar Observatory in Arizona and the Bomem FTS at NRC, Ottawa), with absorption path lengths ranging between 25 and 121 m. The sample Pressures varied between 11 torr (pure CO2) and 924 torr (CO2-air) with volume mixing ratios of CO2 in air between ∼1.5% and 11% (1 torr = 133.322 4 Pa). To minimize systematic errors and increase the accuracy of the retrieved parameters, a constrained multispectrum nonlinear least-squares fitting technique was used to include theoretical quantum mechanical exp...
Heinzwilhelm Hubers - One of the best experts on this subject based on the ideXlab platform.
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high resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser
2006Co-Authors: Heinzwilhelm Hubers, S G Pavlov, Heiko Richter, A Semenov, L Mahler, Alessandro Tredicucci, Harvey E Beere, D A RitchieAbstract:The quantum cascade laser is a powerful, narrow linewidth, and continuous wave source of terahertz radiation. The authors have implemented a distributed feedback device in a spectrometer for high-resolution gas phase spectroscopy. Amplitude as well as frequency modulation schemes have been realized. The absolute frequency was determined by mixing the radiation from the quantum cascade laser with that from a gas laser. The Pressure broadening and the Pressure Shift of a rotational transition of methanol at 2.519THz were measured in order to demonstrate the performance of the spectrometer.The quantum cascade laser is a powerful, narrow linewidth, and continuous wave source of terahertz radiation. The authors have implemented a distributed feedback device in a spectrometer for high-resolution gas phase spectroscopy. Amplitude as well as frequency modulation schemes have been realized. The absolute frequency was determined by mixing the radiation from the quantum cascade laser with that from a gas laser. The Pressure broadening and the Pressure Shift of a rotational transition of methanol at 2.519THz were measured in order to demonstrate the performance of the spectrometer.
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high resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser
2006Co-Authors: Heinzwilhelm Hubers, S G Pavlov, Heiko Richter, A Semenov, L Mahler, Alessandro Tredicucci, Harvey E Beere, D A RitchieAbstract:The quantum cascade laser is a powerful, narrow linewidth, and continuous wave source of terahertz radiation. The authors have implemented a distributed feedback device in a spectrometer for high-resolution gas phase spectroscopy. Amplitude as well as frequency modulation schemes have been realized. The absolute frequency was determined by mixing the radiation from the quantum cascade laser with that from a gas laser. The Pressure broadening and the Pressure Shift of a rotational transition of methanol at 2.519THz were measured in order to demonstrate the performance of the spectrometer.