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The use of organ-on-a-chip (OOC) devices is a promising alternative to existing cell-based assays and animal testing in drug discovery. A rapid prototyping method with polydimethylsiloxane (PDMS) is widely used for developing OOC devices. However, because PDMS tends to absorb small hydrophobic molecules, the loss of test compounds in cell-based assays and increases in background fluorescence during observation often lead to biased results in cell-based assays. To address this issue, we have fabricated a glass-based OOC device and characterized the medium flow and molecular absorption properties in comparison with PDMS-based devices. Consequently, we revealed that the glass device generated a stable medium flow, restricted the absorption of small hydrophobic molecules, and showed enhanced cell adhesiveness. This glass device is expected to be applicable to precise cell-based assays to evaluate small hydrophobic molecules, for which PDMS devices cannot be applied because of their absorption of small hydrophobic molecules.

This work presents an overview of four diatomic iodine molecules for iodine quantification by high-resolution molecular absorption spectrometry, a comparison between the optimal conditions for CaI SrI, BaI, and InI, the consequences of these parameters for the method development and the quantification of iodine in supplements using the diatomic molecules and a simple dilute-and-shoot sample preparation. The thermal behavior of I using Ir, Pt, Zr and W as permanent modifier were studied and compared for each molecule. The concentrations of the forming reagent and the influence of Cl as an interferent were also investigated. The absolute LOD and LOQ values found for iodine using the CaI SrI, BaI, and InI molecules were between 20 ng – 60 ng and 60 ng −200 ng respectively. The concentrations of iodine were in agreement with the producer's stated values, and since there was no significant interference in these samples for this diatomic molecule, an external calibration with aqueous solutions was possible.

In this study, a new therapeutic drug monitoring approach has been tested based on the combination of CaF molecular absorption using high-resolution continuum source absorption spectrometry (HR-CSAS) and surface enhanced Raman spectroscopy (SERS). HR-CSAS with mini graphite tube was successfully tested for clinical therapeutic drug monitoring of the fluorine-containing drug capecitabine in sweat samples of cancer patients: It showed advantageous features of high selectivity (no interference from Cl), high sensitivity (characteristic mass of 0.1 ng at CaF 583.069 nm), low sample consumption (down to 30 nL) and fast measurement (no sample pretreatment and less than 1 min of responding time) in tracing the fluorine signal out of capecitabine. However, this technique has the disadvantage of the total loss of the drug's structure information after burning the sample at very high temperature. Therefore, a new concept of combining HR-CSAS with a non-destructive spectroscopic method (SERS) was proposed for the sensitive sensing and specific identification of capecitabine. We tested and succeed in obtaining the molecular characteristics of the metabolite of capecitabine (named 5-fluorouracil) by the non-destructive SERS technique. With the results shown in this work, it is demonstrated that the combined spectroscopic technique of HR-CSAS and SERS will be very useful in efficient therapeutic drug monitoring in the future.

Conventional theory of dual co-catalysts on a semiconductor in overall water splitting is that the dual co-catalysts spatially separated for photocatalytic H2 and O2 evolution, respectively. However, this theory ignores the use of the surface exciton and the water as a whole molecular for splitting. Here, we put forward a new Yin-Yang hybrid co-catalyst (CoOx-Mo2N) with opposite functions for each component for efficient water splitting. The (CoOx-Mo2N) / Ge3N4 shows activities 1.5 times higher than that Ge3N4 loaded with the spatial separated dual co-catalysts CoOx and Mo2N. The super properties of the Yin-Yang hybrid are attributed to the adjacent spatial configuration for extra use of surface excitons, more favorable water molecular absorption and two electrons reactive path with H2O2 as intermediate involved in water splitting. It is proposed an amendment theory for conventional dual spatially separated co-catalysts by extra using surface exciton via spatially adjacent Yin-Yang hybrid co-catalyst.

Total sulfur concentrations in vinegars were determined using molecular absorption of carbon monosulfide (CS) determined with a high-resolution continuum source flame atomic absorption spectrometer. The molecular absorption of CS was measured at 258.056 nm in an air–acetylene flame. Due to non-spectral interference, as well as the different sensitivities to some sulfur compounds, all sulfur species were oxidized to sulfate using a HNO 3 and H 2 O 2 mixture and the analyte addition technique was applied for quantification. The limit of detection (LOD) and limit of quantification (LOQ) were 11.6 and 38.6 mg L −1 , respectively. The concentrations of sulfur in various vinegars ranged from ⩽LOD to 163.6 mg L −1 .

The ground-state classical path approximation is utilized to compute molecular absorption spectra in a mixed quantum-classical frame. To improve the description for high-frequency vibrational satellites, related quantum correction factors are introduced. The improved method is demonstrated for the Q(y),and Q(x)-bands of pheophorbide a. (C) 2015 Elsevier B.V. All rights reserved.

An analytical procedure for quantitative analysis of sulfur in coal by direct solid sampling graphite furnace high-resolution continuum source molecular absorption spectrometry (HR-CS GF MAS) is described, which is based on the molecular absorption of tin sulfide. The heating program is optimized, and a series of chemical modifiers (Ir, Mg, Pd, Ru, W, Zr) are tested. All measurements are accomplished with an Ir coated platform and Pd as modifier, because the best results are achieved. Accurate results are obtained using the central SnS line of the band found at 271.578 nm with precision values between 1 and 6%. A limit of detection of 10 ng S absolute is achieved. Furthermore, the trueness of the procedure is verified by analysis of certified reference materials. Several coal samples with a concentration range from 0.8 to 21.7 mg g− 1 S and three certified reference materials are analyzed. In all cases, simple calibration with aqueous standards is found to be possible and the sample throughput is 2–3 samples per hour (6 replicates per sample).

A suite of programs for high resolution infrared-microwave atmospheric radiative transfer modeling has been developed with emphasis on efficient and reliable numerical algorithms and a modular approach appropriate for simulation and/or retrieval in a variety of applications. The Generic Atmospheric Radiation Line-by-line Infrared Code — GARLIC — is suitable for arbitrary observation geometry, instrumental field-of-view, and line shape. The core of GARLIC's subroutines constitutes the basis of forward models used to implement inversion codes to retrieve atmospheric state parameters from limb and nadir sounding instruments.This paper briefly introduces the physical and mathematical basics of GARLIC and its descendants and continues with an in-depth presentation of various implementation aspects: An optimized Voigt function algorithm combined with a two-grid approach is used to accelerate the line-by-line modeling of molecular cross sections; various quadrature methods are implemented to evaluate the Schwarzschild and Beer integrals; and Jacobians, i.e. derivatives with respect to the unknowns of the atmospheric inverse problem, are implemented by means of automatic differentiation. For an assessment of GARLIC's performance, a comparison of the quadrature methods for solution of the path integral is provided. Verification and validation are demonstrated using intercomparisons with other line-by-line codes and comparisons of synthetic spectra with spectra observed on Earth and from Venus.

Molecular absorption spectrometry (MAS), originally developed in the 1970s, is a technique to determine non-metals in flames and graphite furnaces by monitoring the absorbance of diatomic molecules. Early studies employed low resolution instruments designed for line source atomic absorption, which provided a limited choice of analytical wavelengths, insufficient spectral resolution, and spectral interferences. However, the development of high-resolution continuum source atomic absorption spectrometry (HR-CS AAS) instrumentation has allowed the analysis of challenging samples for non-metals as well as some difficult elements to determine by AAS, such as aluminum and phosphorus. In this review, theory and analytical considerations for MAS are discussed. The principles and limitations of low resolution MAS are described, along with its applications. HR-CS AAS instrumentation is reviewed, emphasizing performance characteristics most relevant for MAS. Applications of flame and HR-CS GFMAS are reviewed, highlighting the most significant work to date. The paper concludes with an evaluation of the enhanced analytical capabilities provided by HR-CS MAS.

Exoplanets, and in particular hot ones such as hot Jupiters, require a very significant quantities of molecular spectroscopic data to model radiative transport in their atmospheres or to interpret their spectra. This data is commonly provided in the form of very extensive transition line lists. The size of these line lists is such that constructing a single model may require the consideration of several billion lines. We present a procedure to simplify this process based on the use of cross sections. Line lists for water, H$_3^+$, HCN /HNC and ammonia have been turned into cross sections on a fine enough grid to preserve their spectroscopic features. Cross sections are provided at a fixed range of temperatures and an interpolation procedure which can be used to generate cross sections at arbitrary temperatures is described. A web-based interface (www.exomol.com/xsec) has been developed to allow astronomers to download cross sections at specified temperatures and spectral resolution. Specific examples are presented for the key water molecule., Comment: Icarus (submitted)

A novel technique for selecting wavelengths that optimize the temperature precision of absorption-based thermometry is developed. A single universal objective function considering continuous spectral lower-state energy E v ″ , spectral absorbance intensities and an experimental noise level is derived and applied in a brute-force approach to analyze two-wavelength, Doppler-broadened H2O vapor-absorbance thermometry in the 1.33–1.37 μm range. The results reveal the top wavelength pairs and their temperature precisions over a wide temperature range from 280 to 2800 K. Although the spectral database used includes over thousands of transitions in this spectral range, the top pairs are composed of only 12 unique wavelengths. This wavelength selection technique is able to help researchers choose key wavelengths that will perform well in practical applications.

We developed a new radiation parameterization of hydrofluorocarbons (HFCs), using the correlated k-distribution method and the high-resolution transmission molecular absorption (HITRAN) 2004 database. We examined the instantaneous and stratospheric adjusted radiative efficiencies of HFCs for clear-sky and all-sky conditions. We also calculated the radiative forcing of HFCs from preindustrial times to the present and for future scenarios given by the Intergovernmental Panel on Climate Change Special Report on Emission Scenarios (SRES, in short). Global warming potential and global temperature potential were then examined and compared on the basis of the calculated radiative efficiencies. Finally, we discuss surface temperature changes due to various HFC emissions.

The artifacts created in the measurement of phosphorus at the 213.6-nm non-resonance line by electrothermal atomic absorption spectrometry using line source atomic absorption spectrometry (LS AAS) and deuterium lamp background correction (D 2 BC) have been investigated using high-resolution continuum source atomic absorption spectrometry (HR-CS AAS). The absorbance signals and the analytical curves obtained by LS AAS without and with D 2 BC, and with HR-CS AAS without and with automatic correction for continuous background absorption, and also with least-squares background correction for molecular absorption with rotational fine structure were compared. The molecular absorption due to the suboxide PO that exhibits pronounced fine structure could not be corrected by the D 2 BC system, causing significant overcorrection. Among the investigated chemical modifiers, NaF, La, Pd and Pd + Ca, the Pd modifier resulted in the best agreement of the results obtained with LS AAS and HR-CS AAS. However, a 15% to 100% higher sensitivity, expressed as slope of the analytical curve, was obtained for LS AAS compared to HR-CS AAS, depending on the modifier. Although no final proof could be found, the most likely explanation is that this artifact is caused by a yet unidentified phosphorus species that causes a spectrally continuous absorption, which is corrected without problems by HR-CS AAS, but which is not recognized and corrected by the D 2 BC system of LS AAS.

Photoemission results indicate that the initial adsorption of cobaltocene on Cu(1 1 1) at 150 K leads to molecular fragmentation, but with subsequent cobaltocene exposures, molecular absorption occurs. The molecularly adsorbed species is either adsorbed with only a fraction of molecules adopting a preferential orientation along the surface normal or adsorbed with the molecular axis away from the surface normal. This adsorption behavior is compared to nickelocene and ferrocene adsorption.

This paper describes the calculation of the statistical weights and the Einstein A-coefficients for the 39 molecules and their associated isotopologues/isotopomers currently present in the line-by-line portion of the HITRAN database. Calculation of the Einstein A-coefficients was carried out using the HITRAN line intensities and the necessary statistical weights. The Einstein A-coefficient and the statistical weights of the upper and lower levels of the transition were added in the new format of the line parameters for the most recent edition of the HITRAN database.

A brief history and review of the development of some molecular spectroscopic databases is presented. Such databases are compilations of spectroscopic parameters whose principal purpose is to provide the necessary molecular absorption input for transmission and radiance codes. Remote sensing of the terrestrial atmosphere has advanced significantly in recent years, and this has placed greater demands on the compilations in terms of accuracy, additional species, and spectral coverage. This paper discusses current pressing issues, such as the deficiencies in line positions, intensities, and line shape, as well as the directions of future enhancements. To cite this article: L.S. Rothman et al., C. R. Physique 6 (2005).

Nanoparticles of 1-phenyl-3-naphthyl-5-((dimethylamino)phenyl)-2-pyrazoline ranging from tens to hundreds of nanometers were prepared by the reprecipitation method. Their excitonic transitions responsible for absorption and emission, as compared with those of dilute solution, have been investigated as a function of nanoparticle size. We found that pyrazoline nanoparticles possess a special size dependence on their optical properties. As the nanoparticle size decreased, the molecular absorption peak of pyrazoline nanoparticles was observed to shift to the high-energy side due to size effect.

Based on the measurements of molecular absorption and resonance light scattering (RLS), the aggregation of Azur B (AB) was in a medium of pH ranging from 1.98 to 2.56 and ionic strength

The use of molecular absorption spectrometry for the determination of chloride in inorganic solid samples is described. The chloride is measured by monitoring the absorption of vaporised chlorine molecules. The liberation of chlorine is performed by adding concentrated sulphuric acid containing potassium permanganate. The effects of various components commonly present were studied and no serious interference was found. The accuracy was assessed by comparing the results using the proposed method with those obtained by other methods same as well as by artificial samples.

This note provides a brief review of the history and impact of the molecular spectroscopic database known as HITRAN (High Resolution Transmission). We reprint one of the articles describing this database (JQSRT 1998; 60: 665–710), although the series of these papers is among the most cited in the geosciences. HITRAN was established over three decades ago in response to the needs of simulating transmission in the terrestrial atmosphere, and it was enabled by new technology. However the applications of HITRAN, and the requirements on the database, have greatly expanded over the intervening years.

Nanocrystals of 1-phenyl-3-( p -oxymethyl-styryl)-5-( p- oxymethyl-phenyl)-2-pyrazoline (PYB) with different sizes were prepared by the reprecipitation method. The aggregate formation of PYB nanocrystals was found to be J-aggregate, of which the wavelength of absorption peak was observed at about 430 nm. Further, we found that the PYB nanocrystals possess a special optical size-dependent property. As the nanocrystal size decreased, the molecular absorption peak of PYB nanocrystals was observed to shift to the high-energy side due to size effect and at the same time, the J-aggregate absorption peak gradually vanished.

We carried out the observations of bright optical carbon stars by the ISO SWS, and detected the absorption features of CO, CS, CH, SiS and HCN in N-type and SC-type stars. The CH fundamental bands in 3–4 μ m in N-type stars are stronger than those in SC-type stars. On the other hand, the first overtone bands of SiS at 6.6 μ m were detected in WZ Cas (SC-type), while none of them were detected in N-type stars. These results can be explained well by the lower C/O ratio in SC-type stars than in N-type stars. The absorption features of HCN ( ν 1 , ν 2 + ν 3 and ν 1 − ν 2 ) are stronger in SC-type stars than in N-type stars. This fact can be explained by the cooler atmospheres of our sample of SC-type stars due to the lower C/O ratio as well as to the lower effective temperature, compared with our sample of N-type stars. The CS bands and the band heads of the CO fundamental bands are weaker in the observed spectra than in the ones predicted by our model atmospheres. This result cannot be explained by the present model atmosphere and one possible explanation is the contribution by the emission of CO and CS in the outer atmosphere.

Nanocrystals of 1-phenyl-3-((dimethylamino)styryl)-5-((dimethylamino)phenyl)-2-pyrazoline (PYB) with different sizes were prepared by the reprecipitation method. The aggregate formation of PYB nanocrystals was found to be J-aggregate, of which the wavelength of absorption peak was observed at 445 nm. Further, we found that the PYB nanocrystals possessed a special optical size-dependent property. As the nanocrystal size decreased, the molecular absorption peak of PYB nanocrystals was observed to shift to high-energy side due to size effect and the J-aggregate absorption peak gradually vanished simultaneously.

We report on the photodissociation spectroscopy of the weakly-bound complex Al+(C2H4)(O2). Continuum molecular absorption bands are observed in the 218–290 nm spectral region and are assigned to the photoinduced metal-to-ethylene charge-transfer process. Al+ is the dominant photofragment observed at all wavelengths. Two minor chemical dissociation channels are also observed resulting in AlOH+ and AlCH2+ reactive photoproducts. Our experimental investigations are supported by ab initio electronic structure calculations using the Gaussian '94 package.

The vaporization of slurries of Sn and Pb compounds has been followed by the continuous collection of the absorption spectra of the vapour phase. In the case of Sn the formation of SnO(g) has been observed during the vaporization of Sn and SnO2, and the formation of SnS(g) has been observed in the presence of CaSO4 and FeS2. In the case of Pb the only molecular species detected was PbS(g), that originated during the vaporization of PbSO4 in the presence of CaSO4. From the spectral data of the identified species, molecular absorption bands are selected to follow the vaporization process of each species at constant wavelength. The vaporization curves show that SnS(g) evolves before the appearance of Sn atomic vapours, but the formation of SnO(g) occurs contemporaneously with the appearance of the atomic vapours. The vaporization of PbS is slightly delayed in comparison with the formation of Pb atoms.

Direct absorptiometric measurement of aqueous solutions in the UV-visible region is simple but often of little interest because of the featureless shape of the spectra. Automatic resolution methods for deconvolution of the signal are thus required. The choice of the basis of reference spectra is very important and the most appropriate methods use a deterministic approach. These procedures can be added to the software of many new instruments. Some environmental applications are presented.

In this article we report the effect of dynamic disorder in the vicinity of orientational phase transition (Tc=250–260 K) in solid C 60 on reduction of molecular local symmetry. We probe these phenomena by ellipsometry at the wavelength 520 nm, which corresponds to orbitally forbidden molecular absorption of fullerene. The temperature dependence of optical constants of solid fullerene has been compared with its luminescent properties and depolarization of the reflected light. It has been shown that all data exhibit hysteresis-like behavior nearby Tc.

We describe in this paper the modifications, improvements, and enhancements to the HITRAN molecular absorption database that have occurred in the two editions of 1991 and 1992. The current database includes line parameters for 31 species and their isotopomers that are significant for terrestrial atmospheric studies. This line-by-line portion of HITRAN presently contains about 709,000 transitions between 0 and 23,000/cm and contains three molecules not present in earlier versions: COF2, SF6, and H2S. The HITRAN compilation has substantially more information on chlorofluorocarbons and other molecular species that exhibit dense spectra which are not amenable to line-by-line representation. The user access of the database has been advanced, and new media forms are now available for use on personal computers.

A method of simultaneous determination of inorganic As(III) and As(V) is described, which involves arsine generation, measurement of the molecular absorption of arsine in the gas phase at 190 nm and quantification of As(III) and As(V) based on different heights and areas of absorbance versus time profiles of arsine generated from both inorganic species. The limits of detection were 0.5 μg of As(III) and 3 μg of As(V) in a sample volume of 1 ml. An interference study for both species was made and the method was applied to the determination of As2O3 and As2O5 in a standard glass sample.

An improved separative column atomizer (SCA) usable at higher temperatures up to 1350°C has been constructed. Emphasis in this article is on the GC characteristics of an improved separative column atomizer (SCA) module to reduce the interferences caused by background absorption that is often unavoidable in direct analysis of practical samples. By direct AAS analysis, mercury in some organic samples has been successfully determined without background absorption due to non-atomic species resulting from the sample matrices. In the direct atomization of samples in EDTA matrix, however, complete elimination of the background absorption was not possible. Nevertheless, GC separation found in the improved SCA was effective in the measurement of the AA peak free from molecular absorption. Evidences of the GC separation were also given by the analysis of effluent gases.

Studies of serum iron determination have been described using sensitive color reagents of high molar absorptivities. Each selective reaction for iron is strengthened by means of complexing molecules which eliminate trace metal interferences. One ligand. 4-(2-pyridylazo)-resorcinol, exhibits two sensitive peaks, either of which can be used to determine iron quantitatively if an interference is present at one wavelength, or to qualitatively help ensure by ratio measurement that iron is the only metal determined. The second ligand, 2,4-bis(5,6-diphenyl-1,2,4-triazin3-yl) pyridinetetrasulfonic acid, is not only sensitive but has the capability of measuring iron, copper, or both by a judicious choice of selective conditions. Each compound has a useful potential in either discrete sampling or on-stream automation.

Values of photoabsorption cross-sections for some gases have been obtained as a function of wavelength from the ionization threshold to the soft X-ray region. The curves exhibit shoulders which are tentatively compared with some recent theoretical calculations.

Zusammenfassung Eine direkte Bestimmungsmethode von Fluoridspuren durch Messung der GaF-MA in einem Graphitrohratomisator wird beschrieben. Die apparativen Bedingungen (Kompensation der unspezifischen Absorption, Temperaturen der Veraschungsphase und der Phase der Verdampfung/Molekulbildung) wurden optimiert. Der Einfluβ der Ga 3+ - und Na + - Konzentration und der Konzentration verschiedener Sauren auf die Bestimmung wurde untersucht und diskutiert. Hohere Konzentrationen an Ga 3+ -Ionen bewirken eine hohere Konzentration der GaF-Molekule im Plasma des Graphitrohres. Hohere Na + -Konzentrationen bewirken einen geringeren Verlust an HF wahrend der Trocknungsphase. Die Nachweisgrenze (3 s) ist 1,6 ngF - /10 μl; die reziproke Empfindlichkeit ist 0,8 ng F - /10 μl bezogen auf 0,01 E. Der Einflu/GB von Cl - -, Br - -, J - -, SO 4 2- -, BO 3 3- -, SiO 3 2- -, Li + -, K + -, Be 2+ -, Mg 2+ -, Ca 2+ -, Al 3+ -, In 3+ -, Zn 2+ -, Cd 2+ - und Fe 3+ -Ionen auf die Bestimmung wurde untersucht.

Molecular absorption with electrothermal volatilization in a graphite tube. Part 3. A study of the determination of fluoride traces by A1F, GaF, InF and T1F molecular absorption . The use of the molecular absorption of thermally stable molecules such as AlF, GaF, InF and TlF, generated in a normal graphite tube, is assessed for determinations of fluoride. Optimal experimental conditions are discussed. The presence of Na + ions increases the signals. The influence of Na + ions and of other substances is discussed. The sensitivities (0.01 absorbance) are 0.4 ng F - for AlF, 0.8 ng F - for GaF, and 1.1 ng F - for InF.

Photoabsorption cross sections for the methanes CCl 4 , CCl 3 F, CCl 2 F 2 , CClF 3 , CF 4 , CHClF 2 , CHCl 2 F and the ethanes C 2 F 6 , C 2 ClF 5 , C 2 Cl 2 F 4 were measured between 46 and 100 A. In particular, the 0.2 A resolution provides some insight into the Cl 2 p absorption process. It is noted that the molecular cross section for all 8 Cl-containing gases display an L edge “discontinuity” of 3.55±0.15 Mb per Cl atom. The experimental molecular cross sections are compared with sums of atomic cross sections at 100 A using both theoretical and empirical atomic values. The sums of theoretical atomic cross sections describe every experimental molecular value to better than 10%. The sums of empirical atomic cross sections describe molecular values to within 2%.

Molecular absorption, spectrometry with electrothermal volatilization in a graphite tube. Part 5. Determination of iodide traces by molecular absorption of TlI. The molecular absorption of thermally stable TlI, generated by evaporation in a normal graphite cuvette, is suitable for the determination of traces of iodide in small samples. Optimal conditions are described, and interferences are discussed. The reciprocal sensitivities relative to 0.01 absorbance are 80 ng of iodide at 202 nm and 160 ng of ng J- (380.4 nm).

We describe a broad-band uncooled LiF:F + 2 colour centre laser (880–970 nm), pumped by a pulsed Xe-ion laser, for intracavity spectroscopy. Spectra of molecular absorption and gain, and of time-resolved absorption by atomic metastables demonstrate the versatility of the system.

The i.r. and Raman spectra of gaseous and liquid samples of chloroethane-2-d 1 have been observed in the region between 4000 and 200 cm −1 . All of the observed i.r. and Raman active fundamentals have been assigned for the trans and gauche geometrical conformations. The assignments of the fundamentals to the conformers are supported by a normal coordinate calculation, employing the valence force-field of Dempster and Zerbi, which reproduces the observed frequencies with an RMS deviation of 9.5 cm −1 . The molecular absorption features pumped by the CO 2 laser are assigned as the ν 8 and ν 9 modes of the gauche conformer.

From a comparison of simultaneous occultation measurements in Schumann-Runge and Ly- ∞ range in satellite Intercosmos-11 the densities of an additional efficient Ly- ∞ absorbing constituent in the winter-thermosphere are deduced. The results speaking for a remarkable thermospheric water vapor content are supported by the presence of anomalously high temperatures in this height region during the measurement.

Experimental studies of absorption by the free radical OH in the 13.4 GHz region (2Π 3 2 state, J = 7 2 ) have been used to determine collision cross sections of OH with foreign gases. We have performed both direct measurements of linewidths and measurements of absorption saturation over wide pressure ranges. The experimental values are compared with available theoretical values.

A new method based on the optoacoustic effect has been proposed to measure multiple photon absorption at vibrational molecular transitions in a strong IR laser field. Comparison measurements of the average absorbed energy have been done by this method for molecules with different dissociation limits in a strong CO 2 -laser field, the field intensity changed therewith by four orders. For the poly-atomic molecules C 2 H 4 and SF 6 having a comparatively low dissociation limit, the absorption increases monotonously as the power density of laser radiation P increases up to the dissociation limit. For three-atom molecules, such as D 2 O and OCS, absorption saturation takes place with P ≳ 10 MW/cm 2 .

The rotational dependence of Franck-Condon factors has been calculated for OH+, NH+, SiH, MgH+, SiH+, and NO+ using the rotating Morse oscillator model. A rotational dependence is noticed in the electronic bands of each of these molecular species; this dependence may make a significant contribution in the determination of rotational temperatures, abundances and opacity distribution functions.

Measurement of the molecular absorbance at 201 nm of the ammonia gas displaced from strongly alkaline solutions containing ammonium ions provides a rapid, sensitive and selective method for the determination of nitrogen. A simple apparatus based on an atomic absorption spectrometer is described. The method can be applied to the determination of the nitrogen content of soil and plant samples.

A transmittance model was developed for the 200-2000/cm region for interpretation of high spectral resolution measurements of laboratory absorption and of planetary thermal emission. The high spectral resolution requires transmittances to be computed monochromatically by summing the contribution of individual molecular absorption lines. A magnetic tape atlas of H2O,O3, and CO2 molecular line parameters serves as input to the transmittance model with simple empirical representations used for continuum regions wherever suitable laboratory data exist. The theoretical formulation of the transmittance model and the computational procedures used for the evaluation of the transmittances are discussed. Application is demonstrated of the model to several homogenous path laboratory absorption examples.

Errors in atomic absorption spectrophotometric determinations of Pb, Zn, Ni and Co may occur due to the presence of Fe, Al, Ca, Mg, Na and K in the sample solution. At low concentrations of trace element in solution (i.e., up to about 1 p.p.m.) and low concentrations of major elements (up to about 4,000 p.p.m. total cations), the main source of interference is enhancement due to background absorption; this may be corrected by the hydrogen continuum or by use of a non-absorbing wavelength. At higher concentrations of trace element the enhancement due to molecular absorption is partly or completely nullified through suppression caused by major element interference. Similarly, at higher concentrations of major elements, suppression occurs which is probably a function of atomizer efficiency. In these situations, correction for total molecular absorption results in a residual negative error. The errors in determination of Pb, Zn, Ni and Co in geological materials are often ignored in exploration geochemistry work. This restriction on the accuracy of the analytical data is becoming more important with the increasing use of exploration methods based on rock analyses. The errors may be minimized by ensuring that the concentration of both trace element and major element in solution is too low to cause significant suppression effects. Under these circumstances, reasonable results should be obtained through correction for background absorption.

Modulation of the saturation parameter γ2 may be used for a modulation of absorption coefficients α(ω) of molecular absorption lines instead of Stark modulation. The paper describes theory and design of a simple mw-spectrometer which makes use of this saturation effect modulation technique. The spectrometer has been successfully tested in high temperature work. Promising applications to other fields of mw-spectroscopy are discussed.

In atomic absorption, analytical errors arise in the pretreatment steps with carbon atomizers. A procedure is described wherein the entire sample is decomposed and atomized. The products are swept into an absorption tube where atomic absorption and molecular absorption measurements are made. Errors caused by sample loss during pretreatment or by incomplete solvent removal are eliminated.