High Resolution FTIR Spectra Research Articles

Observation and assignment of a high-resolution FTIR-spectrum of T[formula omitted]O, DT16O and HT16O in the range of 4300 to [formula omitted

In the range of 4300 to 4700cm−1, we present analysis of the 2ν1, 2ν2+ν3 and ν1+ν3 bands of T216O, the 2ν1 and ν1+2ν2 of DT16O and the 2ν1 of HT16O. The analysed high-resolution spectrum has been obtained from a Bruker IFS 125HR Fourier-transform spectrometer with a resolution of 0.025cm−1 using an optical cell with an activity of 10GBq. For the in total 2436 lines an individual positional uncertainty of up to 3.4×10-5cm−1 and a systematic uncertainty of 7.5×10-4cm−1 could be achieved. Four of the six bands have been analysed for the first time, the ν1+ν3 band of T216O and the 2ν1 of HT16O have been analysed in previous works of our group. These datasets are extended by 527 new lines and a cross check is confirming the consistency between both works. A comparison of the assigned line positions to the variationally calculated predictions from the Tomsk database agrees with previous findings indicating that band-specific shifts and shifts depending on the rotational quantum numbers are observed leading to an overall difference of up to 0.3cm−1.

Enhancement of oxygen adsorption using biomass-based oxidized porous carbon

The porous carbon adsorbent walnut-shell precursors-based biomass using the Hummer synthesis method was developed for oxidized porous carbon adsorbent. Adsorption-desorption of N2, high-resolution transmission electron microscopy (HRTEM), FESEM, FTIR spectra, and X-ray powder diffraction analyses were used to evaluate the morphology and structure of the specimens. The oxidized porous carbon adsorbent possessed a specific surface area (217.34 m2/g) and pore volume (0.1524 cm3/g). The oxidization process reduced the average volume of mesopores and micropores. Although the specific surface area of the oxidized sample was reduced, the oxygen adsorption capacity was improved by more than 1.4 times. Under 298 K and 9.55 bar pressure, the greatest adsorption capacities for oxygen and nitrogen were specified to be 4.11 (mmol/g) and 3.03 (mmol/g), respectively. The oxygen and nitrogen adsorption on the porous carbon closely was matched by the Fractional-order kinetic and Sips isotherm models, and thermodynamic analysis demonstrated that the physisorption process was confirmed. The improved adsorbent's oxygen adsorption selectivity was remarkable. Oxygen and nitrogen adsorption were increased by oxidized adsorbent by 40% and 14%, respectively. Ultimately, oxygen can be adsorbed by the oxidized sample with more efficiency than nitrogen gas.

Low-Resolution Mid-Infrared Reflection Analysis for Discernment of Contaminants in Seed Cotton

Contaminants mixed with cotton during harvesting and processing dramatically decreases its quality and economic value. A low resolution mid-infrared reflection instrument using four wavelengths (3100, 2900, 2300, and 1500 cm^-1) was designed and constructed to distinguish cotton samples from 16 common contaminants (e.g. plastic and grease). These wavelengths were identified from associated high-resolution FT-IR spectra using multivariable analysis (i.e. Principal Component Analysis, Cluster Analysis, and Multiple Curve Regression).

Low-Resolution Mid-Infrared Reflection Analysis for Discernment of Contaminants in Seed Cotton

Contaminants mixed with cotton during harvesting and processing dramatically decreases its quality and economic value. A low resolution mid-infrared reflection instrument using four wavelengths (3100, 2900, 2300, and 1500 cm^-1) was designed and constructed to distinguish cotton samples from 16 common contaminants (e.g. plastic and grease). These wavelengths were identified from associated high-resolution FT-IR spectra using multivariable analysis (i.e. Principal Component Analysis, Cluster Analysis, and Multiple Curve Regression).

Extended analysis of the high resolution FTIR spectra of H2MS ([formula omitted]) in the region of the bending fundamental band: The ν2 and [formula omitted] bands: Line positions, strengths, and pressure broadening widths

The high resolution infrared spectra of hydrogen sulfide, H2MS (M=32,33,34,36) in the natural abundance (95.041% of H232S, 0.748% of H233S, 4.196% of H234S and 0.015% of H236S), were recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer (Zürich prototype ZP2001) and analyzed in the ν2 fundamental band region (700 – 1800 cm−1). In the experimental spectra 1564, 1019, and 685 transitions were assigned to the ν2 bands of H232S, H234S and H233S (the maximum values of the quantum numbers are Jmax./Kamax. = 24/17, 20/14, 17/14). The subsequent weighted fits of experimentally assigned transitions were made with the Watson Hamiltonian and a set of parameters which reproduces the initial 333/249/216 infrared ro-vibrational energy values has been obtained from the assigned experimental line positions with the root mean square deviations of drms=2.2×10−4 cm−1,1.7×10−4 cm−1 and 1.5×10−4 cm−1 for the H232S, H234S and H233S isotopologues. Additionally, 703, 182 and 23 transitions with the values of quantum numbers Jmax./Kamax. = 18/14, 14/8 and 9/6 belonging to the 2ν2−ν2 hot bands of H232S, H234S and H233S (for the first time for the hot bands of the H234S and H233S species) were assigned in the experimental spectra. Rotational parameters of the ground vibrational state of H236S were re-determined, and, for the first time, 103 transitions (Jmax.=11,Kamax.=8) of the ν2 band of H236S were assigned in the experimental spectra. An analysis of ro-vibrational line strengths of 61 experimental isolated unsaturated and not too weak lines of the ν2 band of H232S was made (Jmax.=9,Kamax.=8), and five effective dipole moment parameters were obtained from the fit which reproduce the initial experimental line intensities with the drms = 1.4 %. An analogous analysis was performed for the H234S and H233S isotopologues. The half-widths analysis was made on the basis of the multi-spectrum fit with the Hartmann-Tran line profile, and self-pressure broadening coefficients were estimated for a few tens of lines for the three most abundant isotopologues.

Extended analysis of the high resolution FTIR spectrum of 32S16O2 in the region of the ν2 band: Line positions, strengths, and pressure broadening widths

The high resolution infrared spectra of sulfur dioxide (32S16O2) were recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer (Zürich prototype ZP2001) in combination with a Ge:Cu detector and analyzed in the ν2 fundamental band region (400–650 cm−1,ν0˜=517.8725691(77) cm−1). More than 4200 transitions were assigned in the experimental spectra to the ν2 band (the maximum values of the quantum numbers are Jmax.=96 and Kamax.=25). The subsequent weighted fit of experimentally assigned transitions was made with the Watson Hamiltonian. The 148 highly accurate MW transitions known from the literature have been also taken into account in the fit, resulting in a set of 33 parameters which reproduces the initial 1295 infrared ro–vibrational energy values from more than 4200 experimental line positions with a root mean square deviation drms=1.5×10−4 cm−1. An analysis of 992 experimental ro–vibrational line intensities of the ν2 band was made, and a set of four effective dipole moment parameters was obtained which reproduces the initial experimental line intensities with a relative drms=5.7%. The half-widths of 146 ro-vibrational lines (Jmax.=53 and Kamax.=20) were analyzed from the multi-spectrum fit, and self-pressure broadening coefficients were determined.

Rovibrational study of the 2ν2 band of D213CO by high-resolution Fourier transform infrared spectroscopy

The high-resolution FTIR spectrum of the 2ν2 band (3250–3380 cm−1) of D213CO was recorded at an unapodized resolution of 0.0063 cm−1. A total of 747 rovibrational transitions have been assigned and fitted up to J″ = 32 and Ka″ = 10 using the Watson’s A-reduced Hamiltonian in the Ir representation. A set of accurate upper state (v2 = 2) rovibrational constants, three rotational and five quartic centrifugal distortion constants, were determined for the first time. The band center of the 2ν2 band was found to be 3326.765109 ± 0.000079 cm−1. The rms deviation of the rovibrational fit was 0.00096 cm−1.

Line intensity measurements and analysis in the ν3 band of ruthenium tetroxide

Ruthenium tetroxide (RuO4) is a heavy tetrahedral molecule characterized by an unusual volatility near ambient temperature. Because of its chemical toxicity and the radiological impact of its 103Ru and 106Ru isotopologues, the possible remote sensing of this compound in the atmosphere has renewed interest in its spectroscopic properties. The present contribution is the first investigation dealing with high-resolution line-by-line intensity measurements for the strong fundamental band observed near 10 μm, associated with the excitation of the infrared active stretching mode ν3. It relies on new, high resolution FTIR spectra recorded at room temperature, using a specially constructed cell and an isotopically pure sample of 102Ru16O4. Relying on an effective Hamiltonian and associated effective dipole moment [S Reymond–Laruinaz et al, J Mol Spectrosc 2015;315:46–54], the measured line intensities were assigned and dipole moment parameters determined. A HITRAN-formatted frequency and intensity line list was generated.

High-resolution infrared spectroscopy and analysis of the ν2/ν4 bending dyad of ruthenium tetroxide

RuO4 is a heavy tetrahedral molecule of interest in several fields. Due to its chemical toxicity and radiological impact of its 103 and 106 isotopologues, the possible remote sensing of this compound in the atmosphere has renewed interest in its spectroscopic properties. We investigate here, for the first time at high resolution, the bending modes region in the far infrared. High resolution FTIR spectra have been recorded near room temperature, using a specially designed cell and an isotopically pure sample of 102RuO4. New assignments and effective Hamiltonian parameter fits for the main isotopologue (102RuO4) have been performed, treating the whole ν2/ν4 bending mode dyad. We provide precise effective Hamiltonian parameters, including band centers and Coriolis interaction parameters.

The high-resolution FTR spectrum of ethane between 3170 and 3430 cm−1

The high resolution FTIR spectrum of ethane has been reinvestigated in the region near 3μm, where three perpendicular and one parallel infrared active bands are found.The main perpendicular band is ν4+ν10. It is shown that the perpendicular partners of the combinations ν4+2ν8 and ν4+2ν11 are coupled with each other in such a way that only one resultant mode can interact effectively with ν4+ν10, becoming detectable by intensity stealing. The third perpendicular band is found to be the hot (2ν4+ν10)−ν4, lying at about 33cm−1 below the cold ν4+ν10, because of the strong anharmonicity of the torsional mode ν4, and then well separated cold and hot transitions occur in this region. It is suggested that they could be exploited in the temperature monitoring in atmospheric and planetary spectra.The complexity and the irregular rotation–torsion structure makes an analysis of this perpendicular system not practicable, but a considerable body of new line assignments, especially for the hot transitions, have been found.We have been able to analyze the parallel band, in spite of the anomalous torsional structure, and some peculiar torsional effects show that the vibrational upper state must be the infrared active ν2+ν9+ν12(A2u).A total of 304 transitions of this active parallel band were fitted with a rms deviation of 0.0097cm−1 to derive band parameters, and interacting parameters from the perturbers 3ν4+ν11∓1+ν12∓1 and ν11±1+ν9∓1+ν12±1/ν11±1+ν9±1+ν12∓1.

Re-analysis of the high resolution FTIR spectrum of C2H2D2-cis in the region of 1280–1400 cm−1

The high-resolution infrared spectrum of C2H2D2-cis ethylene was analyzed in the region of 1280–1400cm−1, where the strong ν12 band is located. More than 2000 transitions (about three times more than it was made in the preceding studies) were assigned with the maximum values of the upper quantum numbers Jmax.=45 and Kamax.=19 (Jmax.=31 and Kamax.=13 in the preceding studies). For the first time, 22 transitions belonging to the 2ν10 weak band were assigned. For description of the assigned transitions (upper ro-vibrational energy levels), the Hamiltonian model was used which takes into account resonance interactions between the vibrational state (v12=1) and three other closely located states: (v10=2), (v8=v10=1), and (v3=1). A set of 43 spectroscopic parameters obtained from a weighted least square fit reproduces the initial experimental data (817 upper energy values and more than 2000 transitions) with the drms=2.2×10−4cm−1 which is close to experimental uncertainties and considerably better than in prior studies. Ground state rotational and centrifugal distortion parameters were improved on the basis of the IR experimental data of the present study and microwave data from the earlier literature.

Analysis of high resolution FTIR spectra from synchrotron sources using evolutionary algorithms

Room temperature Fourier transform infrared spectra of the four-membered heterocycle trimethylene sulfide were collected with a resolution of 0.00096cm−1 using synchrotron radiation from the Canadian Light Source from 500 to 560cm−1. The in-plane ring deformation mode (ν13) at ∼529cm−1 exhibits dense rotational structure due to the presence of ring inversion tunneling and leads to a doubling of all transitions. Preliminary analysis of the experimental spectrum was pursued via traditional methods involving assignment of quantum numbers to individual transitions in order to conduct least squares fitting to determine the spectroscopic parameters. Following this approach, the assignment of 2358 transitions led to the experimental determination of an effective Hamiltonian. This model describes transitions in the P and R branches to J′=60 and Ka′=10 that connect the tunneling split ground and vibrationally excited states of the ν13 band although a small number of low intensity features remained unassigned. The use of evolutionary algorithms (EA) for automated assignment was explored in tandem and yielded a set of spectroscopic constants that re-create this complex experimental spectrum to a similar degree. The EA routine was also applied to the previously well-understood ring puckering vibration of another four-membered ring, azetidine (Zaporozan et al., 2010). This test provided further evidence of the robust nature of the EA method when applied to spectra for which the underlying physics is well understood.

Re-analysis of the (100), (001), and (020) rotational structure of SO2 on the basis of high resolution FTIR spectra

Three infrared spectra, weak (W), medium (M), and strong (S), of the 32SO2 molecule were recorded with high resolution in the 1000–1500cm−1 region. Spectra were recorded with the Fourier Transform interferometer Bruker IFS-120 HR in Oulu (Finland) with different pressures, absorption path lengths, and recording time. That allowed us to record not only the ν1 and ν3 bands with higher values of quantum numbers J and Ka than it was made earlier, but to record for the first time very weak 2ν2 band. In this case, transitions with the values Jmax./Kamax. equal to 89/37, 109/28, and 54/9 were assigned in the experimental spectra for the bands ν1, ν3, and 2ν2, respectively. As it became clear in the course of the analysis, the rotational parameters of the ground vibrational state, known in the literature, do not describe suitably the ground state combination differences (GSCD) for the states with the value Ka>26–27. As a consequence, the ground state rotational parameters were improved on the basis of our experimental data. The 12131 transitions assigned in the experimental spectrum (7618, 3952, and 561 transitions of the bands ν1, ν3, and 2ν2, respectively) were used for determination of ro-vibrational energy values of the vibrational states (100), (001), and (020). The lasts were used then in the fit procedure together with known in the literature high accurate sub-millimeter wave data. Resonance interactions between all three vibrational states have been taken into account in the Hamiltonian used for the fit. As a result, the 51 varied parameters, obtained from the fit, reproduce 4063 ro-vibrational energies of the states (100), (001), and (020) (12131 initial experimental transitions) with accuracies close to experimental uncertainties: the rms deviation is 6.1×10−5cm−1, 9.7×10−5cm−1, and 13.9×10−5cm−1 for our FTIR data (for the (100), (001), and (020) states, respectively), and comparable with experimental uncertainties for heterodyne data.

铝掺杂锆酸钕纳米晶的制备以及对甲基橙的催化降解

以硝酸锆、硝酸铝和硝酸钕作为原材料，甘氨酸水溶液和无机盐作为溶剂和分散剂，通过盐助甘氨酸溶液燃烧法(salt-assistant gly combustion method, SGCM)制备了具有立方晶系的烧绿石型铝掺杂锆酸钕纳米晶。产物经X-射线粉末衍射、透射电镜、高分辨电子显微镜、傅里叶变换红外光谱以及拉曼光谱表征。结果表明：钕离子被铝离子部分替代而保持原有烧绿石结构，制得的纳米粒子具有较完美的晶体结构，分散性较好，热处理温度在700℃时单一相的Nd2−xAlxZr2O7纳米晶已完全形成；所制得的纳米晶由平均粒径为10~30 nm的球状粒子组成，根据Scherrer公式计算出的平均粒径为14.5 nm；从透射电镜照片的(222)面的晶面距为0.305 nm，与理论计算值一致。以光催化降解甲基橙为探针，考察复合产物的催化活性。检测到相对于Nd2Zr2O7而言，Al3+的掺杂可以明显的提高它的催化性能，当nAl:nNd = 1:19时其催化活性最强。 Cubic pyrochlore type aluminium ion doped neodymium zirconate nanocrystals were prepared by salt- assistant gly combustion method (SGCM) with zirconium nitrate, aluminum nitrate and neodymium nitrate as raw materials, glycine as the incendiary agent and inorganic salt as solvent and dispersant. The products were characterized by XRD, TEM, HRTEM, High-resolution electron microscopy, FT-IR and Raman spectrum. The results showed that neodymium ions were partially substituted by aluminium ions, while maintaining the original pyrochlore structure. The obtained nano particles had a perfect crystal structure and good dispersion. Single phase Nd2−xAlxZr2O7 nanocrystals al-ready fully formed with the heat treatment temperature in 700°C. The obtained nanocrystals were consisted of spheroidal particles with the average grain size of 10 - 30 nm. According to the Scherrer formula, the calculated mean grain size is 14.5 nm. The crystal plane distance from the (222) plane in the photo of transmission electron microscopy is 0.305 nm, which is consistent with the theoretical calculated value. The catalytic activity of the composite product is determined by the reaction speed of photocatalytic degradation of methyl orange. It is detected that compared to Nd2Zr2O7, the doping of Al3+ can obviously improve its catalytic performance. When nAl:nNd = 1:19, it has the strongest catalytic activity.

High resolution spectroscopy and the first global analysis of the Tetradecad region of methane 12CH4

We present the first detailed analysis of the infrared spectrum of methane (12)CH4 in the so-called Tetradecad region from 2.1 to 1.6 μm (4760-6250 cm(-1)). New experimental high resolution FTIR spectra at 78 K and at room temperature combined with improved theoretical modeling have allowed quantum assignments to be greatly extended in this region. A global fit of all assigned lines of (12)CH4 in the 0-6200 cm(-1) region has been performed. In the end, 3012 line positions and 1387 intensities of 45 individual subbands of the Tetradecad were modeled up to J = 14. The root mean square deviations were 0.023 cm(-1) for line positions and 13.86% for line intensities in the Tetradecad region itself. Although this analysis is still preliminary, it is already sufficient to characterize the stronger bands throughout the whole of the Tetradecad. The calculated integrated intensity of the polyad is 1.399 × 10(-19) cm(-1)/(molecule cm(-2)) at 296 K. A "definitive" theoretical modeling of this spectral region of methane requires further work, but the present success substantially improves our understanding of methane spectroscopy as needed to interpret planetary atmospheres. Lines pertaining to three-fourths of the 60 sub-vibrational bands in this polyad have been assigned.

Structural, vibrational, and rovibrational analysis of tetrafluoroethylene

High resolution FTIR spectra of (13)C enriched tetrafluoroethylene (C(2)F(4)) were measured at 150 K at the Australian Synchrotron. Rovibrational transitions were assigned in the a-type symmetric and b-type antisymmetric CF(2) stretches of (12)C(13)CF(4) and (13)C(2)F(4) near 1170 cm(-1) and 1300 cm(-1), respectively. Ground vibrational state spectroscopic constants for both molecules were determined in addition to the upper state constants for ν(11) and ν(9) of (13)C(2)F(4) and ν(11), ν(2)+ν(6), and ν(5) of (12)C(13)CF(4). The ground state constants, along with those determined for the (12)C(2)F(4) isotopologue from previously published data, were used to determine a semi-experimental r(e) structure r(CC) = 132.36 ± 0.37 pm, r(CF) = 131.11 ± 0.23 pm, α(FCC) = 123.3 ± 0.3° in excellent agreement with ab initio structures. Lower resolution FTIR spectra were measured between 100 and 5000 cm(-1) at room temperature and band centres obtained for all modes of the three isotopologues; although only 5 out of 12 modes in (12)C(2)F(4) and (13)C(2)F(4) are infrared (IR) active, the others were inferred from combination and hot-band positions. A number of modes are observed to be infrared active only in the (12)C(13)CF(4) isotopologue due to its lower symmetry. Most notably, decoupling of the antisymmetric CF(2) motions in the two halves of (12)C(13)CF(4) results in 2 strongly IR active modes that involve motion at one carbon or the other.

THE FAR-INFRARED ROTATIONAL SPECTRUM OF ETHYLENE OXIDE

High-resolution FTIR spectra of ethylene oxide have been measured in the far-infrared region using synchrotron radiation. A total of 1182 lines between 15 and 73?cm?1 were assigned, with J max?= 64, expanding upon previous studies that had recorded spectra up to 12?cm?1, J max?= 49. All available data were co-fitted to provide greatly imp- roved rotational constants for the ground vibrational state that are capable of predicting transitions up to 73?cm?1.

High resolution FTIR spectrum of cyanogen iodide between 200 and 5000 cm−1. Global rovibrational analysis of IR and MW data for I12C14N

The infrared absorption spectrum of ICN has been recorded in the region 200–5000cm−1 with a Bruker 120HR interferometer, and several tenthousands of lines have been measured with a precision between 0.0001 and 0.001cm−1. Most of these lines have been assigned. These new data were combined with transitions previously measured in the microwave and millimeterwave ranges. After a band-by-band analysis including 292 subbands a rovibrational global analysis has been performed using all available data. The main resonances are the rotational ℓ-type resonance and the strong Fermi resonance coupling the states ν1=1 and ν2=2 via the cubic anharmonic constant k122. In addition, many local resonances became evident by the observation of the corresponding avoided crossings. In particular, there is a direct coupling between the states (400) and (240) due to the fourth-order resonance k112222. There is also a fourth-order Coriolis resonance governed by C11222 responsible for interactions between the (200) and (030) states. All these interactions have been taken into account in one-step diagonalization procedures. A statistical agreement with the 6344 selected pieces of data has been obtained, with an estimated standard deviation σˆ=0.660. All those data and their deviations are given in the first depository. A set of 109 parameters including 24 off-diagonal anharmonic and Coriolis resonance parameters has been derived. They have been used to calculate effective rovibrational parameters for all substates up to more than 6000cm−1, also listed in the second depository.

Low Temperature Matrix Isolation IR-Spectroscopy and Quantum Chemical Study of β-Alanine Structure

In this study we have focused on conformational structure of the β-alanine molecule isolated in low-temperature argon matrices. The main purpose was to determine the set of the β-alanine conformers, which can occur in the matrices. Matrix isolation FTIR-spectroscopy was combined with quantum chemical calculations performed by the MP2 and DFT(B3LYP) methods using the aug-cc-pVDZ and aug-cc-pVTZ basis sets. Gibbs free energies of the β-alanine conformers also were calculated at the CCSD(T)/CBS level of theory.Totally 21 β-alanine conformers were found at the MP2/aug-cc-pVDZ level of theory. But 10 of them are separated from lower energy conformers by low energy barriers and they can not present in the matrixes. High-resolution FTIR spectra were registered for the samples immediately after deposition as well as for the samples which were UV irradiated or annealed to 25K. Both the UV irradiation and the matrix annealing result in redistribution of the band intensities in the FTIR spectra. It allows us to distinguish spectral bands of different β-alanine conformers. Assignment of the spectral bands was performed based on calculated vibrational spectra of the β-alanine conformers. As a result we detected presence of 4 β-alanine conformers in the Ar matrices.Further data about β-alanine conformational structure can be used in molecular dynamics simulations and also they can be useful for searching of β-alanine in the interstellar space.Key words: β-alanine, matrix isolation, quantum chemical calculations.

Convenient solvent-free synthesis and characteristics of acid–base bifunctionalized MCM-41 mesoporous silicas

A series of acid–base bifunctionalized mesoporous silicas have been successfully synthesized by means of a convenient solvent-free approach. Through grinding the precursors, aluminium and magnesium nitrates, with the as-prepared MCM-41, and then the generation of acid–base sites and removal of host template were simultaneously completed in the subsequent calcination procedure. The resultant modified mesoporous silicas MgO–Al2O3–MCM-41 were characterized with X-ray diffraction, high-resolution transmission electron microscopes, N2 adsorption, FT-IR spectra, 29Si and 27Al MAS NMR, NH3− and CO2− temperature programmed desorption. The results indicate that the products exhibit excellent acid–base properties with well mesoporous structure, and the guests were well dispersed in the channel of MCM-41, which make it exhibit high activity for the synthesis of EMC.