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International audience; The Monitoring Nitrous Oxide Sources (MIN2OS) satellite project aims at monitoring global-scale nitrous oxide (N2O) sources by retrieving N2O surface fluxes from the inversion of space-borne N2O measurements that are sensitive to the lowermost atmospheric layers under favorable conditions. MIN2OS will provide emission estimates of N2O at a horizontal resolution of 1° × 1° on the global scale and 10 × 10 km2 on the regional scale on a weekly to monthly basis depending on the application (e.g., agriculture, national inventories, policy, scientific research). Our novel approach is based on the development of: 1) a space-borne instrument operating in the Thermal InfraRed domain providing, in clear sky conditions, N2O mixing ratio in the lowermost atmosphere (900 hPa) under favorable conditions (summer daytime) over land and under favorable and unfavorable (winter nighttime) conditions over the ocean and 2) an atmospheric inversion framework to estimate N2O surface fluxes from the atmospheric satellite observations. After studying three N2O spectral bands (B1 at 1240–1350 cm−1, B2 at 2150–2260 cm−1 and B3 at 2400–2600 cm−1), a new TIR instrument will be developed, centered at 1250–1330 cm−1, with a resolution of 0.125 cm−1, a Full Width at Half Maximum of 0.25 cm−1 and a swath of 300 km. To optimally constrain the retrieval of N2O vertical profiles, the instrument will be on-board a platform at ~830 km altitude in a sun-synchronous orbit crossing the Equator in descending node at 09:30 local time in synergy with two other platforms (Metop-SG and Sentinel-2 NG) expected to fly in 2031–32 aiming at detecting surface properties, agricultural information on the field scale and vertical profiles of atmospheric constituents and temperature. The lifetime of the MIN2OS project would be 4–5 years to study the interannual variability of N2O surface fluxes. The spectral noise can be decreased by at least a factor of 5 compared to the lowest noise accessible to date with the Infrared Atmospheric Sounding Interferometer-New Generation (IASI-NG) mission. The N2O total error is expected to be less than ~1% (~3 ppbv) along the vertical. The preliminary design of the MIN2OS project results in a small instrument (payload of 90 kg, volume of 1200 × 600 × 300 mm3) with, in addition to the spectrometer, a wide field and 1-km resolution imager for cloud detection. The instruments could be hosted on a small platform, the whole satellite being largely compatible with a dual launch on VEGA-C. The MIN2OS project has been submitted to the European Space Agency Earth Explorer 11 mission ideas.

Extreme ultraviolet (XUV) capillary-discharge lasers (CDLs) are a suitable source for the efficient, clean ablation of ionic crystals, which are obviously difficult to ablate with conventional, long-wavelength lasers. In the present study, a single crystal of cesium iodide (CsI) was irradiated by multiple, focused 1.5-ns pulses of 46.9-nm radiation delivered from a compact XUV-CDL device operated at either 2-Hz or 3-Hz repetition rates. The ablation rates were determined from the depth of the craters produced by the accumulation of laser pulses. Langmuir probes were used to diagnose the plasma plume produced by the focused XUV-CDL beam. Both the electron density and electron temperature were sufficiently high to confirm that ablation was the key process in the observed CsI removal. Moreover, a CsI thin film on MgO substrate was prepared by XUV pulsed laser deposition; a fraction of the film was detected by X-ray photoelectron spectroscopy.

Vertical-Cavity Surface-Emitting Laser (VCSEL) diodes are among the youngest members of the semiconductor laser diode family. The main aim of our work focuses on the measurement of the basic properties (the spectral range of the laser emission, temperature and current tunability) of experimental VCSEL diode lasers based on GaSb operating in the infrared region around 4250 cm−1. A high-resolution FTIR Bruker IFS 120 HR spectrometer with a maximum resolution of 0.0035 cm−1 was used in the emission setup for the laser diagnostic research. The absorption spectra of atmospheric pollutants like methane, carbon monoxide and ammonia have been measured using these VCSELs for the first time.

Time- and spatially-resolved optical emission spectroscopy was performed to characterize the plasma produced in a hybrid magnetron-sputtering-laser deposition system, which is used for TiC or SiC thin films preparation. A graphite target was ablated by a KrF excimer laser (λ=248 nm,τ=20 ns) and either Ti or Si targets were used for DC magnetron sputtering in argon ambient. Spectra were measured in the range 250–850 nm. The evolution of the spectra with varying magnetron powers (0–100 W) and argon pressures (0.3–10 Pa) was studied. Spectra of the plasmas produced by a) the magnetron alone, b) the ablation laser alone, and c) the magnetron and the ablation laser together, were recorded. Spectra (a) were dominated by Ar atoms and Ar+ ions. Emission lines of Ti and Si were detected, when Ti target and Si target was used, respectively. Spectra (b) revealed emission of C, C+, C2, Ar, Ar+. Spectra (c) showed presence of all previously mentioned species and further of Ti+ ions emission was detected.

The sub-millimetre radiometer (SMR) instrument aboard the Odin satellite launched in February 2001 is dedicated to the observation of trace gas profiles in the stratosphere and in the mesosphere, in particular water vapour and its isotopic species HDO, H2 17O and H2 18O. By averaging more than 400 000 Odin/SMR spectra over the period from November 2002 to March 2003, weak lines have been detected in the atmosphere. These weak lines have been attributed to water isotopic species HD18O, to a vibrationally-excited N2O, and to CH3OH.

We have applied two spectroscopic techniques in order to investigate air pollution dispersion in real and simulated atmosphere: the Titan–Sapphire laser technique based on differential absorption lidar (DIAL), and CO 2 laser photoacoustic spectrometry (LPS). A set of spatial NO 2 measurements was performed over a highway outside a city and in an urban street canyon with extensive traffic. Qualitative agreement was found between the results obtained by DIAL and by physical modeling based on LPS measurements in a wind tunnel.

The formation and decay of carbon and nitrogen atoms, CN radicals and C2 molecules were monitored using spatial- and time-resolved emission spectroscopy in a plasma plume formed during laser ablation of a graphite target in nitrogen atmosphere. A simple exponential model was used to explain the effect of the individual chemical reactions and plasma dynamics on the measured kinetic characteristics. The succession of emissions C N CN was observed in the time-resolved spectra, supporting the suggestion that the CN radical is formed mainly by the direct reaction C + N CN or C2 + N2 2CN. The formation of CN radical was enhanced by the additional generation of atomic nitrogen through the RF discharge. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Plasma processes during CN x films deposition were studied in a pulsed laser deposition system equipped with a KrF excimer laser (500 mJ, 20 ns). The laser plasma was characterized in a pressure range from 2 to 100 Pa of nitrogen gas. We report on an optical emission spectroscopy, which was used for a spatial and time resolved investigation of the plasma species. Analysis includes estimation of vibrational and rotational temperatures of the CN molecule.

The article describes the manufacture and testing of a new type of semiconductor laser working at low temperatures (12–100 K) in the wavelength range 3200–3300 cm-1. This kind of laser can be tuned in the modal range up to 6 cm-1 and is characterized by a narrow spectral line width (about 7 MHz).

1310 nm wavelength VCSELs produce single mode emission in excess of 1 mW in the temperature range of 20-70°C with a very low relative intensity noise of -148 dB/Hz. These devices have a broad tuning range of ~50 cm -1 with variable temperature and current, which covers multiple absorption lines of methane, ammonia and hydrogen fluoride. With these VCSELs, we report optical absorption spectroscopy of several gases near 1310 nm wavelength. In particular, we report for the first time detection of HF using the absorption line in the vicinity of 7568 cm -1 with an estimated low-pressure detection limit at the level of several ppm.

The inverse Laplace transformation method was used to interpret the time-resolved emission spectra of Sr * and describe the dynamics of the laser plume formed in the laser ablation of Pb-Bi-Sr-Ca-Cu-O. Three kinds of processes characterized by rate constants b 1 , b 2 and b 3 were found in the laser plume. The rate constant of the slowest process b 3 increases with the pressure and can be assigned to deexcitation of Sr * . The next two rate constants b 1 and b2 describe processes occurring during the laser pulse and immediately after it.

CO 2 laser photoacoustic spectroscopy was used for quantitative analysis of a multicomponent gaseous mixture of pollutants with similar chemical structures (toluene, ortho -, para - and meta -xylenes) in trace concentrations (50–700 ppm). The agreement with the results of gravimetric measurements was better than 5% in most cases. The following detection limits were found for this method in the given arrangement: 3.57±0.04 ppm for toluene, 1.82±0.02 ppm for o -xylene, 1.00±0.01 ppm for p -xylene and 2.86±0.04 ppm for m -xylene. Determination of the concentration using the classical least squares method was compared with a method based on the principle of calculation of the lowest component entropy. While the least squares method yielded the most selective analysis when four lines were used for four-components mixture, introduction of the component entropy yielded an increase in the selectivity level by measurement of six lines.

Absolute line intensities of sixteen rovibrational transitions in the ν4 band of 14NH3 were measured around 1800 cm−1 using a tunable diode laser spectrometer with a sweep modulation of the laser frequency. Individual laser scans over the line region were recorded to disk storage separately and the spectrum accumulation was performed off-line using a computer to reduce a significant line broadening because of a lower accuracy of the hardware on-line accumulation. From integrated absorption coefficients obtained by the numerical analysis of the measured line profile, the effective transition moments of individual rovibrational lines were derived. Using the second order perturbation theory of the transition moment of rovibrational transitions of the symmetric top molecules, the effective vibrational transition moments for the ν4 fundamental band of 14NH3 were estimated.

Laser photoacoustic spectrometry and a line permeation pollution source were used in a study of the dispersion of pollution in an urban agglomerate using simulation in a wind tunnel. Applications of this measuring technique utilize the high sensitivity and broad dynamic range (3 orders of magnitude in this case) of the photoacoustic detection method. The minimum detected absorbance in the photoacoustic detection method employed in this work was at the level of ≅ 4.3 × 10–6 (≅ 8 µg m–3 CH3OH). The effectiveness and flexibility of the permeation method for generation of various concentrations of gases were verified for simulation of emission pollution sources in a wind tunnel. The line permeation pollution source developed in this work, with a concentration flux of (8.3 × 10–5 ± 2 × 10–6) g s–1 at 20 °C, generated a concentration level in the model used from a background value of 80–90 µg m–3 up to values of ≅ 1000 µg m–3 of methanol. A simple model street canyon together with the pollution source was employed to carry out a number of measurements of spatial profiles. The dispersion of the pollutant was studied at the bottom and on the walls of the street canyon together with the concentration variation with changes in the wind speed. The laboratory model was used to demonstrate the differences in ventilation of the street canyon.

The performance of the InAsSbP/InAs lasers for absorption spectroscopy of ammonia at 3370–3660 cm−1 was first shown. These continuous wave lasers based on the III–V semiconductor are alternative to a widespread utilised Pb-salt device and were first investigated in closed-cycle He-cryostat at temperatures of 32–85 K. The spectral and tuning characteristics of the laser were considered versus both heatsink temperatures and drive currents in viewpoint of applications in molecular laser spectroscopy, with best device performance being found at 45–65 K. The preliminary experiments to record spectra of the ammonia absorption with the diode were undertaken.

VCSEL (Vertical-Cavity Surface-Emitting Laser) diodes are the youngest members of the semiconductor laser diode family. The main target of our work is focused on the modally characterization and the measurement of the basic properties (threshold current, spectral range of the laser emission, the current tunability) of the three VCSEL diode based on GaSb matrix, which are emitting in the infrared region around 4250 cm−1. We used high resolution FTIR spectrometer Bruker IFS 120 HR with the maximum resolution 0.0035 cm−1 in the emission setup for the laser diagnostic research. The spectra of atmospheric pollutants like methane, carbon mono-oxide and ammonia, which have several absorption lines in studied spectral range have been measured using vertical cavity surface emitting lasers for the first time. Lasers were also used for investigation of these gases by absorption spectroscopy.

The article reports the results of different methods of modelling releases and dispersion of dangerous gases or vapours in cases of major accidents from road and rail transportation in urban zones. Transport accidents of dangerous substances are increasingly frequent and can cause serious injuries in densely inhabited areas or pollution of the environment. For quantitative risk assessment and mitigation planning, consequence modelling is necessary. The modelling of dangerous substance dispersion by standard methods does not fully represent the behaviour of toxic or flammable clouds in obstructed areas such as street canyons. Therefore the predictions from common software packages as ALOHA, EFFECTS, TerEx should be augmented with computational fluid dynamics (CFD) models or physical modelling in aerodynamic tunnels, and further studies are planned to do this. The goal of this article is to present the results of the first approach of modelling using these standard methods and to demonstrate the importance of the next development stage in the area of transport accident modelling of releases and dispersions of dangerous substances in urban zones in cases of major accident or terrorist attacks.

A decrease in the lasing threshold with increasing temperature has been observed in InAs/InAsSbP laser heterostructures for the 2.7–2.9 μm spectral range at cryogenic temperatures (T=32–85 K). At temperatures below 50 K a negative characteristic temperature, T0=−70 K, was obtained for the threshold current. Characteristics of the temperature dependence of the threshold current and the laser output power were investigated.

Mn2(CO)10 was photolysed in the gas phase by the XeCl-excimer laser with fluence in the range 25–300 mJ/cm2 and a dye laser. The UV/VIS emission of the products was probed on a nanosecond time scale. The emission from excited states of metal atoms was detected only. The Mn atoms are predominantly formed in their ground statea6S2 1/2. The absorption of one photon and the subsequent relaxation process leads to the formation ofz6P J 0 (J = 11/2, 21/2, 31/2) states and emission of photons at a wavelength of 403 nm. The formation of the excited statese8D5 1/2,z6F 4 1/2 0 ande6D4 1/2 and the subsequent emission observed at wavelengths of 357, 383 and 446 nm requires the absorption of two photons by the ground-state Mn atoms. In addition, transition from thea6Dj (J = 11/2, 21/2) lower states were observed in the wavelength-resolved Laser-Induced Fluorescence (LIF) spectra.

The time dependence of attenuation of the He‐Ne and CO2 laser beams passing through a plume produced by the excimer laser ablation of Y‐Ba‐Cu‐O in the air is characterized by two maxima. The first maximum is apparently caused by a change in the refractive index at the front of the shock wave and is propagated with a velocity of 360 m s−1 comparable with the speed of sound at room temperature and it is independent on laser energy. The initial velocity for the second maximum is ∼20 m s−1 and can be connected with scattering on species ablated from the superconductor surface. The velocity of ablated species increases linearly with laser energy; the change is 81 m s−1 J−1.

Physical simulation was used to study pollution dispersion in a street canyon. The street canyon model was designed to study the effect of measuring flow and concentration fields. A method of CO2-laser photoacoustic spectrometry was applied for detection of trace concentration of gas pollution. The advantage of this method is its high sensitivity and broad dynamic range, permitting monitoring of concentrations from trace to saturation values. Application of this method enabled us to propose a simple model based on line permeation pollutant source, developed on the principle of concentration standards, to ensure high precision and homogeneity of the concentration flow. Spatial measurement of the concentration distribution inside the street canyon was performed on the model with reference velocity of 1.5 m/s.

Properties of the plasma plume produced on a bismuth (Bi) target irradiated by a focused extreme-ultraviolet (XUV) capillary-discharge laser beam were investigated. Langmuir probes were used in both single- and double-probe arrangements to determine the electron temperature and the electron density, providing values of 1–3 eV and ∼1013–1014 m−3, respectively. Although the temperatures seem to be comparable with values obtained in ablation plasmas produced by conventional, long-wavelength lasers, the density is significantly lower. This finding indicates that the desorption-like phenomena are responsible for the plume formation rather than the ablation processes. A very thin Bi film was prepared on an MgO substrate by pulsed XUV laser deposition. The non-uniform, sub-monolayer character of the deposited bismuth film confirms the Langmuir probe's observation of the desorption-like erosion induced by the XUV laser on the primary Bi target.

The formation of triplet states of photosensitizers and singlet oxygen during reactions sensitized by protoporphyrin IX dimethyl ester (PPDME) and the products of its photo-oxidation in solution were studied by time-resolved spectroscopy. Irradiation with long-wavelength light (670 nm), which is absorbed by the products of photo-oxidation of PPDME, provides lower quantum yields of singlet oxygen than in sensitization with PPDME alone, which absorbs light with a wavelength of 630 nm. Spectroscopic measurements also confirmed the lower rate of sensitized photo-oxidation of bilirubin during irradiation with light with a wavelength of 670 nm.

The properties of plasma formed during pulsed laser deposition from a Bi–Sr–Ca–Cu–O target were measured using a Langmuir probe in the electron accelerating region “Plasma splitting” was observed at pressures in the range of 1–5 Pa and distances of the probe from the target of 3–14 mm.

Freons are typical pollutants coming mostly from sprays. They also find industrial use as refrigerants. Since they could restrict the Earth’s ozone layer, their sensitive and selective detection is important. For this purpose, the laser optoacoustic (OA) method [1,2] may be advantageous, especially when a tunable CO2 laser of sufficient power is available.