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The RNA world hypothesis suggests that early cellular ancestors relied solely on RNA molecules for both genetic information storage and cellular functions. RNA, composed of four nucleosides—adenosine, guanosine, cytidine, and uridine—forms the basis of this theory. These nucleosides consist of purine nucleobases, adenine and guanine, and pyrimidine nucleobases, cytosine and uracil, bonded to ribose sugar. Notably, carbonaceous chondrite meteorites have revealed the presence of these bases and sugar, hinting at the potential existence of nucleosides in space. This study aims to present the infrared spectra of four RNA nucleosides commonly found in terrestrial biochemistry, facilitating their detection in space, especially in astrobiological and astrochemical contexts. Laboratory measurements involved obtaining mid- and far-IR spectra at three temperatures (−180 °C, room temperature, and +180 °C), followed by calculating molar extinction coefficients (ε) and integrated molar absorptivities (ψ) for corresponding bands. These spectral data, along with ε and ψ values, serve to provide quantitative insights into the presence and relative abundance of nucleosides in space and aid in their detection. [ABSTRACT FROM AUTHOR]

In order to quantitatively analyze the proportions of independent components in mixtures, it is necessary to extract line spectra corresponding to those components from the spectrum signal of some mixture and evaluate the amplitude of the spectral lines. Multiple factors cause the drift and tilt of a spectrum signal's baseline, such as environment noises, instrument bias, and sample size, which affect the identification and quantitative analysis of the line spectra superimposed on the baseline. Therefore, the baseline of a spectrum signal should be removed before the line spectra are identified. A baseline correction algorithm based on Catastrophe Point detection and Lipschitz exponent's analysis is proposed in this paper. With the algorithm, the strong spectral lines are identified and removed, and then the spectral baseline is evaluated without the interference of strong spectrum signals. First, catastrophe points are located based on the local modulus maxima theory of wavelet coefficients. Second, according to the Lipschitz exponent theory, the strong spectral peaks' regions are identified and removed by a smoothing filter. Then the slowly varying spectrum is segmented adaptively and fitted by the least square fitting method. After the segments are attached and the boundaries are smoothed, the baseline of the spectrum is acquired and extracted finally. The algorithm is more accurate than classical ones because identifying the baseline is implemented after strong peaks are removed, so their influences to baseline extracting are eliminated. The results of experiments show that the algorithm is accurately performed for the spectrum signal of a gas mixture, S F 6 . [ABSTRACT FROM AUTHOR]

We have studied the intensity of the spectral lines for the main components in clay: Al I 309.4 nm, Al II 358.7 nm, Mg II 279.6 nm, Ti II 323.6 nm vs. the position of the object relative to the focus of the optical system when the samples are exposed to single laser pulses from a YAG:Nd3+ laser. We have determined the permissible ranges for positioning the object relative to the focus of the optical system (positive and negative defocusing) for which there is practically no change in the reproducibility of the intensity for the spectral lines for red and white clay samples. We show that the position of the object relative to the focus of the optical system should be within the range ΔZ ~ ±1.5 mm for optimal laser pulse energies for the analyte spectral lines. We have calculated the radiation flux density for different laser pulse energies and different distances from the focus to the object. We have shown experimentally that reducing the radiation flux density leads to a decrease in the intensity of the analyte spectral lines. [ABSTRACT FROM AUTHOR]

The technique for precise measurements of wavelengths in the range around 222 nm (45030 cm-1) has been presented. The reciprocal linear dispersion of the spectrometer was 0.529 Å/mm. The measurements were made in the second spectral order for a grating with 2400 lines/mm. Identification of emission lines of hollow cathode lamp (Fe) was made in the spectral range 4428...4452 Å. The wavelengths were measured for 32 identified lines in the spectrum. The mean square error of measurements is ~0.0005 Å. [ABSTRACT FROM AUTHOR]

A new approach is presented in this paper to link optical emission spectrum analysis to the quality of clad layers produced with laser metal deposition (LMD). A Nd:YAG laser ( λ = 1.064 μm) was used to produce clad tracks with Metco 42C powder on AISI 4140 steel substrate. The laser power was ramped in steps of 220 W from 800 W to 2780 W focusing the laser beam into a 4.8 mm diameter spot. A constant cladding speed of 10 mm s −1 is used with a powder feeding rate of 0.36 g s −1 . The extent of metallic bonding is evaluated from dilution data obtained by measuring the melt depth in the substrate from cross sections of the clads. The spectra generated during the deposition process were collected with an optical spectrometer attached to the laser head. The discrete spectral lines from the collected spectra were identified from the NIST database as Fe I and Cr I lines. Two different spectral analysis methods were used, namely the calculation of the electron temperature T e and the intensity ratio IR. The electron temperature T e is computed from four discrete Cr I lines at 526.415, 529.827, 532.834, and 534.044 nm wavelength. The intensity ratio IR is a measure of the absorption of a discrete Fe I line at 588.91 nm. The analysis of the collected spectra indicates that onset and extent of metallic bonding can be detected with a spectrometer during the deposition process. A sudden decrease of the IR signal during the LMD process indicates the onset of metallic bonding. A further increase of the laser power mainly contributes to an increase in melt depth, leading to a higher dilution. In this region, the T e signal shows a better correlation with the dilution. [ABSTRACT FROM AUTHOR]

Abstract: A comparison of the atmospheric absorption calculated with different data banks of water vapour absorption lines is made. The HITRAN database, Barber-Tennyson line list (BT2), calculation of Partridge and Schwenke (PS) are considered. The contribution of H2O lines, absent in HITRAN, to the atmospheric transmission, calculated with 10cm−1 spectral resolution in the 10000–20000cm−1 spectral region is up to 1.5% for a vertical path and 4% for a solar zenith angle of 70deg. The highest difference is observed in the 940nm band. The incoming fluxes of solar radiation, measured by a rotating solar spectroradiometer, were modeled with BT2 and HITRAN database. The difference between measured and calculated fluxes does not exceed the instrumental uncertainties. [Copyright &y& Elsevier]

The extended crossed-beam method has been used to study excitation of high-lying levels in the tungsten atom. 40 excitation cross sections of WI spectral lines have been measured for exciting electron energy 50 eV. Two optical excitation functions were recorded in the electron energy range 0–200 eV. The results obtained were used to calculate the total excitation cross sections of 24 odd WI energy levels. [ABSTRACT FROM AUTHOR]

Using the methods of numerical simulation, we have investigated the dependence of the intensity and parameters of the spectral line profiles in the radiation of semitransparent plasma on its optical thickness, the degree of inhomogeneity, and the parameter distribution. As a model, we used the equilibrium plasma of argon with a given temperature profile on the observation line. The calculation has been performed for the spectral lines of the argon atom characterized by different broadening constants. On the basis of the results obtained it has been shown that it is possible to diagnose the plasma and determine the degree of its inhomogeneity and reabsorption by the parameters of the self-reversed profiles of the spectral lines. To diagnose the plasma in the absence of self-reversal, we propose to use the line intensities in the emission spectra of the plasma, including those obtained by probing it by its self-radiation. [ABSTRACT FROM AUTHOR]

The characteristic features of the formation of the spatial energy spectra of extended holes of millimeter cross section illuminated by radiation of different wavelengths have been investigated. The fundamental possibility of determining the diameter of an extended hole is shown. The main analytical expressions relating the radius of the hole to diffraction orders have been found. [ABSTRACT FROM AUTHOR]

This paper presents a timing recovery method for VSB receivers based on a square-law device that uses both in-phase and quadrature-phase signals. Existing timing recovery schemes use second-order statistics of the real component of the VSB signals or rely on the fourth order statistics of the VSB signal magnitude. We propose an alternative timing recovery approach for VSB signals based on a square-law device that produces a DC tone with carrier phase information and a timing tone with timing frequency information. [ABSTRACT FROM AUTHOR]