Asymmetric Stretch Vibration Research Articles

Exploiting Hydrogen Interaction of Drugs and Biodegradable Scaffolds Using Nanoparticles Loaded Nanofibers

AbstractThis study presents a detailed investigation of the structural and surface modifications of Fe3O4 nanoparticles (NPs). Fourier Transform Infrared (FTIR) spectroscopy was utilized to analyze the distinct characteristic peaks of Fe3O4 NPs and their subsequent modifications with stearic acid (ST) layers. The FTIR analysis revealed characteristic peaks at 580 cm−1, and 441 cm−1, corresponding to the Fe‐O stretching vibrations of the bulk Fe3O4 NPs. The successful loading of stearic acid onto the Fe3O4 NPs was confirmed by the appearance of new peaks at 1413 cm−1 and 2908 cm−1, indicative of the asymmetric CH2 stretch and CH3 umbrella vibration modes of stearic acid. UV‐Vis spectroscopy further corroborated the efficient loading of tetracycline and ibuprofen onto Fe3O4/DST nanoparticles, as evidenced by changes in absorption spectra. N2 adsorption‐desorption isotherms illustrated the presence of micro and meso pores on the surface of Fe3O4 NPs, with alterations in pore volume and diameter post‐surface modification and drug loading. Evaluation of magnetic properties indicated a reduction in saturation magnetization after surface modification and drug loading, attributed to changes in homogeneity and surface moments. Differential Reflectance Spectroscopy (DRS) and Raman spectroscopy elucidated distinctive peaks and shifts in spectra, confirming the composition and structural changes in drug‐loaded nanofibers.

Incorporation of papaya (Carica papaya L.) leaf extract into cornhusk for glutinous rice snack packaging application

The present work was performed to evaluate the potency of papaya leaf extract (PLE) to improve the characteristics of cornhusk as a packaging material for glutinous rice snack (GRS). Total phenolic, tannin, and saponin contents of PLE were 7.41 ± 0.65 mgTAE/mL, 1.80 ± 0.70 mgTAE/mL, and 11.78 ± 0.36 mgDE/mL, respectively. The presence of bioactive compounds on the surface of GRS was confirmed by Fourier transform infrared spectroscopy analysis. Characteristic bands for saponin were caused by the stretching vibration of C=O (at 1744 cm-1) as well as C‒O and C‒C vibrations (at 1051 cm-1). Tannin was identified as C‒O asymmetric stretch vibration at 1051 cm-1 and C‒H out of plane vibration at 926 and 866-867 cm-1. The antioxidant activity of PLE was found to be 49.53 ± 2.67%. The reductions of total plate counts (TPC), yeast and mould counts (YMC), and Aspergillus flavus-A. parasiticus counts on PLE-incorporated cornhusks after 24 h were in the range of 0.2 - 1.2 log CFU/cm2, and retained the loads below 2 log CFU/cm2 during 14-d storage. PLE decreased the water vapour transmission rate of the cornhusk due to the particles of the extract adhering to the cornhusk surface, as supported by the result of the scanning electron microscopy of PLE-incorporated cornhusk. The incorporation of PLE also increased elongation without reducing the tensile strength of the cornhusk significantly. There were reductions of TPC, YMC, and Aspergillus flavus-A. parasiticus counts of GRS ranging from 0.4 - 2.3 log CFU/g using PLE-incorporated cornhusks during storage. GRS rancidity was minimised by PLE-incorporated cornhusks. Owing to its bioactive compound, PLE could be incorporated into the cornhusk to improve packaging characteristics and controls microbial contamination of GRS while retarding the rancidity.

Real-Time Infrared Spectroscopic Measurement of Natural Moisturizing Factor

Real-Time Infrared Spectroscopic Measurement of Natural Moisturizing Factor

Site-selective dynamics of ligand-free and ligand-bound azidolysozyme.

Azido-modified alanine residues (AlaN3) are environment-sensitive, minimally invasive infrared probes for the site-specific investigation of protein structure and dynamics. Here, the capability of the label is investigated to query whether or not a ligand is bound to the active site of lysozyme and how the spectroscopy and dynamics change upon ligand binding. The results demonstrate specific differences for center frequencies of the asymmetric azide stretch vibration, the longtime decay, and the static offset of the frequency fluctuation correlation function (FFCF)-all of which are experimental observables-between the ligand-free and the ligand-bound N3-labeled protein. The center-frequency shifts range from 1 to 8 cm-1, which is detectable from state-of-the art experiments. Similarly, the nonvanishing static component Δ0 of the FFCF between ligand-free and ligand-bound protein can differ by up to a factor of 2.5. This makes the azide label a versatile and structurally sensitive probe to report on the dynamics of proteins in a variety of environments and for a range of different applications. Ligand-induced differences in the dynamics are also mapped onto changes in the local and through-space coupling between residues by virtue of dynamical cross correlation maps. This demonstrates that the position where the label is placed also influences the local and global protein motions.

An effect of extra compactified dimensions of space in the molecule hbox {NO}_{{2}}

The theory of large extra compactified dimensions of space (ADD-model) predicts that gravity may become strong in a compactification space of the size of a molecule and may affect the vibrational motion of a molecule. In triatomic molecules like hbox {NO}_{{2}} nuclear dynamics is strongly coupled to electronic dynamics at the intersection of electronic states (conical intersection). We discuss experimental results on hbox {NO}_{{2}} which reveal that the collision-free molecule optically excited into a symmetric stretch vibration mode of an electronic state with conical intersection undergoes an irreversible non-radiative transition into an asymmetric stretch vibration mode in combination with a change of the electronic state. We suggest ascribing this irreversible non-radiative transition to a gravitational perturbation on the vibrational motion in hbox {NO}_{{2}}. This gravitational perturbation deactivates the upper state of the optical transition. The width of the absorption line is given by the characteristic time of the gravitational perturbation and not by the radiative lifetime of the excited molecular state.Graphical abstract

Contact pairs of RNA with magnesium ions-electrostatics beyond the Poisson-Boltzmann equation

The electrostatic interaction of RNA with its aqueous environment is most relevant for defining macromolecular structure and biological function. The attractive interaction of phosphate groups in the RNA backbone with ions in the water environment leads to the accumulation of positively charged ions in the first few hydration layers around RNA. Electrostatics of this ion atmosphere and the resulting ion concentration profiles have been described by solutions of the nonlinear Poisson-Boltzmann equation and atomistic molecular dynamics (MD) simulations. Much less is known on contact pairs of RNA phosphate groups with ions at the RNA surface, regarding their abundance, molecular geometry, and role in defining RNA structure. Here, we present a combined theoretical and experimental study of interactions of a short RNA duplex with magnesium (Mg2+) ions. MD simulations covering a microsecond time range give detailed hydration geometries as well as electrostatics and spatial arrangements of phosphate-Mg2+ pairs, including both pairs in direct contact and separated by a single water layer. The theoretical predictions are benchmarked by linear infrared absorption and nonlinear two-dimensional infrared spectra of the asymmetric phosphate stretch vibration which probes both local interaction geometries and electric fields. Contact pairs of phosphate groups and Mg2+ ions are identified via their impact on the vibrational frequency position and line shape. A quantitative analysis of infrared spectra for a range of Mg2+-excess concentrations and comparison with fluorescence titration measurements shows that on average 20–30% of the Mg2+ ions interacting with the RNA duplex form contact pairs. The experimental and MD results are in good agreement. In contrast, calculations based on the nonlinear Poisson-Boltzmann equation fail in describing the ion arrangement, molecular electrostatic potential, and local electric field strengths correctly. Our results underline the importance of local electric field mapping and molecular-level simulations to correctly account for the electrostatics at the RNA-water interface.

Comparison of chemical compositions in wood and bark of Persian silk tree (Albizia julibrissin Durazz.)

ABSTRACT This research was conducted to identify and compare the chemical compositions in Persian silk tree (Albizia julibrissin Durazz.) from different parts of wood and bark, using Fourier Transform Infrared (FTIR) Spectroscopy, gas and liquid chromatography coupled to mass spectrometry (GC-MS, LC-MS), and elemental analysis. FTIR analysis showed significant differences in the chemical structure of bark and wood at peaks that belong to the cellulose and hemicelluloses. According to the results, the C-O-C asymmetric stretch vibration in cellulose and hemicelluloses peak of Persian silk tree was lower in the bark and ѵC=O in quinone or p-quinone peak was higher in the bark. The results of GC-MS showed 12 chemical constituents in the bark and 43 in the wood, respectively. Among these, hexadecanoic acid and inositol were in common. According to the LC-MS analyses, bark samples were rich in lignan compositions and triterpenoid saponins, whereas wood was poor in these compositions. Altogether 61 compositions have been tentatively identified and described from bark and wood tissues; many of them were identified for the first time. Energy-dispersive X-ray (EDX) spectrometry illustrated that the bark contained iron and aluminium, sodium, phosphorus, sulphur and chlorine, while these elements did not exist in wood.

Detection and assignment of ozone bands near 95% of the dissociation threshold: Ultrasensitive experiments for probing potential energy function and vibrational dynamics

Ozone formation and depletion play a key role in various physical and chemical atmospheric processes which remain to be understood in more detail. The modeling of such phenomena based on ozone dynamics calculations requires a detailed knowledge of quantum states, transition probabilities, and ozone potential energy surface (PES) near the dissociation threshold ${D}_{0}$. Knowledge of highly excited rovibrational states with energies approaching ${D}_{0}$ is necessary for a reliable interpretation of satellite measurements of the ozone absorption or emission in the upper atmosphere in nonlocal thermodynamic equilibrium conditions. In addition, these states provide an ideal probe of PESs computed by ab initio methods but their detection by absorption spectroscopy is particularly challenging due to the sharp decrease of the intensity with the energy of the corresponding vibrational combination and overtone bands. In this work, two very high-energy vibrational bands are detected by high sensitivity cavity ring-down spectroscopy providing a noise equivalent absorption ${\ensuremath{\alpha}}_{\mathrm{min}}$ on the order of a few ${10}^{\ensuremath{-}11}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$. The corresponding cold bands, assigned as ${\ensuremath{\nu}}_{1}+6{\ensuremath{\nu}}_{2}+3{\ensuremath{\nu}}_{3}$ and $6{\ensuremath{\nu}}_{1}+{\ensuremath{\nu}}_{2}+{\ensuremath{\nu}}_{3}$ centered at 7969 and $7993\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$, respectively, are about nine orders of magnitude less intense than the well-known ${\ensuremath{\nu}}_{3}$ fundamental band near 10 \textmu{}m. The spectrum analysis allowed for the experimental determination of 240 rovibrational energy levels of the upper vibrational states. The corresponding rotational patterns, located between 93.1% and 96.7% of the dissociation threshold, are the most excited ones measured so far by absorption spectroscopy. The values of the band centers and rotational constants derived from the spectrum analysis provide further confirmation of the absence of an activation barrier on the minimum-energy path towards the dissociation threshold [Tyuterev et al., Phys. Rev. Lett. 113, 143002 (2014)]. The vibrational dynamics is discussed in the context of the radiative transition probabilities and related Einstein coefficients for the observed bands. Another important question in the context of the nuclear dynamics concerns the interaction among the three identical potential wells of the ozone molecule in the ground electronic state, which appears to be due to the Jahn-Teller effect. Recent theoretical results accounting for the three potential wells in a full symmetry approach predicted that vibration states should exhibit deviations from the conventional one-potential-well ab initio calculations, near the dissociation threshold. In the present work, we observe a better agreement of the experimentally determined energy value with the three-wells prediction for the (1,6,3) vibrational state involving a large simultaneous excitation of both bending (${\ensuremath{\upsilon}}_{2}=6$) and asymmetric stretch (${\ensuremath{\upsilon}}_{3}=3$) vibrations pointing towards a nearby well. This could be tentatively interpreted as a manifestation of the three-wells effect.

The Identification of Multiple Crystalline Zinc Soap Structures Using Infrared Spectroscopy.

The formation of crystalline zinc soaps (zinc salts of fatty acids) in oil paint layers is a common sign of paint degradation. In this study, we have used infrared spectroscopy to systematically identify differences in structure and composition of crystalline zinc soap phases, and report data analysis methods for structure attribution in challenging oil paint samples. Supported by reported crystal structures, it was possible to distinguish two distinct types of zinc soap geometry: a highly symmetrical packing for long-chain saturated soaps (type B) and an alternating packing for zinc soaps with short, unsaturated, or dicarboxylic chains (type A). These two types of packing can be identified by a single or split asymmetric COO stretch vibration band. With this new information, we studied the structure and composition of zinc soaps formed in a zinc white model paint and in a cross-section from the painting Equations in Space by Lawren Harris. Using non-negative matrix factorization, band integration and band position maps, it was possible to clearly identify zinc azelate in the model paint and map its spatial distribution. The same methods showed that the paint cross-section contained both types of zinc soap structure within the same paint layer, with the less symmetrical structure appearing only at the interface with the ground layer. The results give valuable information on the internal chemistry of oil paint layers, and the demonstrated methods can find widespread application for in-depth analysis of infrared microscopy data.

Modification and characterization of chicken eggshell for possible catalytic applications

Researchers have shown considerable interest in finding a sustainable, low cost, and readily available substitute for the commercial calcium oxide (CaO) catalyst. In this work, raw chicken eggshell was modified by boiling and calcination at 900 °C for 3 h. The x-ray diffraction characterization revealed that while the proportion of CaCO3 in the raw and boiled samples was found to be 79.3 % and 99.2 % respectively, the CaCO3 had been converted to 63.8 % CaO and CO2 in the calcined sample. This was due to the thermal decomposition during calcination. The outcome of the infrared spectroscopy showed that the raw and boiled chicken eggshell presented a similar absorption profile with peaks at 1 394 cm−1, 873 cm−1, and 712 cm−1, which were as a result of the presence of asymmetric stretch, out-of-plane bend, and in-plane bend vibration modes. The major peaks presented by the calcined sample at 3642 cm−1 can be attributed to the OAH stretching vibration and bending hydroxyl groups present in Ca(OH)2. The Brunauer-Emmett-Teller surface areas for the raw, boiled and calcined chicken eggshell were found to be 2.33 m2/g, 3.26 m2/g, and 4.6 m2/g respectively, indicating increased catalytic activity of the calcined sample. Overall, boiling was found to have a negligible effect on the chicken eggshell, while high-temperature calcination greatly affected the pore size, surface area, composition, and thermal decomposition profile of the chicken eggshell sample.

Atypical vibrational interactions

Chemical Physics Vibrational energy transfer (VET) between solute molecules is generally unfavorable in liquids because of weak intermolecular forces. Xiang et al. measured the two-dimensional infrared spectrum of a molecular mixture, W(CO)6 and W(13CO)6, with saturated concentrations in a binary solvent embedded in an optical microcavity. This experiment showed that the VET between the asymmetric stretch vibrations of two solute molecules is enhanced via polaritonic intermediate states formed by a strong coupling with the cavity mode. The efficiency is modulated by the cavity lifetime, which provides an opportunity to control the VET process in the liquid phase. This could lead to various practical implementations. Science , this issue p. [665][1] [1]: /lookup/doi/10.1126/science.aba3544

Effects of microwave-assisted hydrothermal treatment and beta particles irradiation on the thermoluminescence and optically stimulated luminescence of SrMoO4 powders

SrMoO4 powders, produced by co-precipitation, are investigated employing thermoluminescence (TL) and optically stimulated luminescence (OSL). The effects of microwave-assisted hydrothermal (MAH) treatment, beta particle irradiation, and thermal treatment are studied to understand their role on defect density and location in the band-gap. The powder X-ray diffraction showed that the SrMoO4 powders crystallize in a tetragonal structure. The raman studies confirmed the presence of active vibration modes characteristic of molybdates, whereas the Fourier Transformed Infrared (FTIR) data exhibit the symmetric and asymmetric stretch vibrations. The trapping depth energies, determined from TL glow curves, range from 0.9 eV to 1.95 eV. The TL data show that the MAH treatment decreases the defect density and favors the formation of defects with lower activation energies. The residual TL signal shows the formation of shallower traps with a glow peak occurring at lower temperatures. The OSL emission only taken place for samples submitted to heating cycles and depends on the heating rate. These results indicate that shallow traps induced by thermal treatment are responsible for the OSL signal. The shape and intensity of the OSL curve depend on the number of heating cycles and on the heating rate, revealing that thermal treatment has a profound influence on this emission. The OSL signal for MAH-treated SrMoO4 samples subjected to thermal treatment increases linearly with beta irradiation dose. The results give insight that SrMoO4 phosphors may have potential applications in the design of a radiation sensor.

Mode resolved heating dynamics in pulsed microwave CO2 plasma from laser Raman scattering

Efficient CO2 reduction is predicted for CO2 microwave plasma by virtue of predominant excitation of the asymmetric stretch vibration. Although interpretation of ongoing research is generally based on this mechanism, direct measurement of the power partitioning to support the assumed preferential vibrational excitation in CO2 microwave plasma is currently lacking. Here, such measurements are performed on a 100 µs pulsed microwave CO2 discharge. The <1% duty cycle ensures low gas temperature conditions at the discharge onset. Raman and Rayleigh scattering are employed to reveal vibrational, rotational, and gas temperatures in a spatially and temporally resolved manner. A novelty in the approach is that asymmetric stretch excitation is determined from the bending—symmetric stretch Raman spectrum. During the first 40 µs a significant inter-vibrational non-equilibrium is observed with the symmetric stretch and bending temperature reaching 750 K and the asymmetric stretch temperature reaching 1150 K. A maximum rotational-vibrational non-equilibrium occurs after 60 µs when the rotational temperature is half of the 1150 K vibrational temperature. Rotational and translational modes are measured to be in equilibrium at all times. The power partitioning is analyzed to estimate the power consumed by vibrational excitation, which is used to estimate the reduced electric field in the discharge. This work confirms strong vibrational excitation in CO2 microwave plasma albeit less predominant than often assumed.

Pancreatic lipase inhibitory activity of soil Aspergillus species isolates from Egypt

By using sum frequency generation vibrational spectroscopy (SFG), the structure of sodium deoxycholate (NaDC, a kind of bile salts) at air/solution interface was analyzed at molecular level, and its effects on Candida rugosa lipase (CRL) and Porcine pancreatic lipase (PPL) adsorption were revealed. When NaDC was incubated with lipase first, lipase was activated at low NaDC concentration (≤CMCNaDC, critical micelle concentration of NaDC). While when NaDC was incubated with the substrate p-nitrophenyl palmitate (p-NPP) first, the activity of lipase was almost completely inhibited, since NaDC adsorbed onto the substrate interface and presented a barrier for lipase approach. The surface tensions of lipase solution declined with the increase of NaDC, which indicated that there was competitive adsorption at the air/solution interface. With increasing concentration of NaDC, the symmetric stretch vibration of CH2 groups at 2853 cm−1, the asymmetric stretch vibration of CH3 groups at 2960 cm−1 and amide I vibration at 1655 cm−1, supposedly caused by lipase amino residues, gradually reduced and eventually disappeared. When NaDC concentration reached high (≥CMCNaDC), the SFG spectra became similar with the pure NaDC spectra, which was direct evidence that NaDC had completely replaced the lipase molecules at the air/solution interface.

Do extra compactified dimensions of space cause a substructure underlying the expected eigenstates of a molecule?

Experimental results on NO2 are explained based on the ADD-model of large extra compactified dimensions of space. We assume that gravity is sufficiently strong in a compactification space of the size of the molecule to affect the vibrational motion of the nuclei by causing an asymmetric perturbation in the symmetric stretch vibrational motion of the optically excited state. At the same excitation energy, there are also other electronic states of different symmetry (conical intersection of potential energy surfaces), which may couple with the optically excited state. Due to the gravitational perturbation the nuclei being in the symmetric stretch vibration mode of the optically excited electronic state pass over into the asymmetric stretch vibration mode of an isoenergetic electronic state. This parity conserving change of the vibronic wave function enhances a small gravitational perturbation to an optically detectable signal. The perturbation is associated with a time constant of about 3 μs, which we attribute to fluctuations of the shape of the compactification space induced by a background cosmic field.

A new six-dimensional ab intito potential energy surface and rovibrational spectra for the Ar–H2S complex

A new six-dimensional potential energy surface for the Ar–H2S complex involving the , and normal modes for the symmetric stretch vibration, bending vibration and asymmetric stretch vibration of H2S was reported. The potential was calculated at the coupled-cluster singles and doubles with non-iterative inclusion of connected triples [CCSD(T)]-F12a. The vibrationally averaged potentials with H2S at the vibrational ground state as well as the and excited states were generated from the six-dimensional potential. Each potential was found to have a planar T-shaped global minimum, a planar local minimum, two first-order saddle points and a second-order saddle point. The global minimum is located at , and with a well depth of 179.24 cm−1. The radial discrete variable representation/angular finite basis representation method and the Lanczos algorithm were employed to calculate the rovibrational energy levels for Ar–H2S with H2S at the vibrational ground and excited states. The predicted vibrational band origins are redshift by −0.38 and −0.63 cm−1 of the Ar–H2S in the and regions of H2S, respectively. The rotational frequencies were in good agreement with the experimental values, which were within 0.5% of the observed dates.

Probing vibrational coupling via a grid-based quantum approach-an efficient strategy for accurate calculations of localized normal modes in solid-state systems.

In this work an approach to investigate the properties of strongly localized vibrational modes of functional groups in bulk material and on solid‐state surfaces is presented. The associated normal mode vectors are approximated solely on the basis of structural information and obtained via diagonalization of a reduced Hessian. The grid‐based Numerov procedure in one and two dimensions is then applied to an adequate scan of the respective potential surface yielding the associated vibrational wave functions and energy eigenvalues. This not only provides a detailed description of anharmonic effects but also an accurate inclusion of the coupling between the investigated vibrational states on a quantum mechanical level. All results obtained for the constructed normal modes are benchmarked against their analytical counterparts obtained from the diagonalization of the total Hessian of the entire system. Three increasingly complex systems treated at quantum chemical level of theory have been considered, namely the symmetric and asymmetric stretch vibrations of an isolated water molecule, hydroxyl groups bound to the surface of GeO2 (001), ‐quartz(001) and Rutil (001) as well as crystalline Li2NH serving as an example for a bulk material. While the data obtained for the individual systems verify the applicability of the proposed methodology, comparison to experimental data demonstrates the accuracy of this methodology despite the restriction to limit this methodology to a few selected vibrational modes.The possibility to investigate vibrational phenomena of localized normal modes without the requirement of executing costly harmonic frequency calculations of the entire system enables the application of this method to cases in which the determination of normal modes is prohibitively expensive or not available for a particular level of theory. © 2018 Wiley Periodicals, Inc.

Modelling the input and relaxation of vibrational energy in CO2 plasmas

A consistent theoretical analysis of a pulsed DC glow discharge operating at pressure of 5 Torr, current of 50 mA and plasma pulse of 5 ms in CO2 is presented. The model couples the electron Boltzmann equation to a rate balance equations involving ~70 individual vibrational states. The kinetic scheme and the corresponding e–V, V–T and V–V rate coefficients are validated via comparison between the model predictions and recent experimental data available in literature. The bending and symmetric vibrational levels show a continuous increase along the plasma pulse while the levels in the asymmetric mode present a maximum at around 0.7 ms. A corresponding maximum of the temperature of the asymmetric stretch vibration mode is observed as well at the start of the pulse reaching a value of about 900 K, well above the vibrational temperatures of the symmetric and bending modes, which remain always nearly equilibrated. A quick thermalization of the CO2 vibrational temperatures is always observed in the afterglow.

Structural sensitivity of C[sbnd]H vibrational band in methyl benzoate

The CH vibrational bands of methyl benzoate are studied to understand its coupling pattern with other vibrational bands of the biological molecule. This will facilitate to understand the biological structure and dynamics in spectroscopic as well as in microscopic study. Due to the congested spectroscopic pattern, near degeneracy, and strong anharmonicity of the CH stretch vibrations, assignment of the CH vibrational frequencies are often misleading. Anharmonic vibrational frequency calculation with multidimensional potential energy surface interprets the CH vibrational spectra more accurately. In this article we have presented the importance of multidimensional potential energy surface in anharmonic vibrational frequency calculation and discuss the unexpected red shift of asymmetric CH stretch vibration of methyl group. The CD stretch vibrational band which is splitted to double peaks due to the Fermi resonance is also discussed here.

Time evolution of vibrational temperatures in a CO2 glow discharge measured with infrared absorption spectroscopy

Vibrational temperatures of CO2 are studied in a pulsed glow discharge by means of time-resolved in situ Fourier transform infrared spectroscopy, with a 10 μs temporal resolution. A method to analyze the infrared transmittance through vibrationally excited CO2 is presented and validated on a previously published CO2 spectrum, showing good agreement between fit and data. The discharge under study is pulsed with a typical duty cycle of 5–10 ms on–off, at 50 mA and 6.7 mbar. A rapid increase of the temperature of the asymmetric stretch vibration (T3) is observed at the start of the pulse, reaching 1050 K, which is an elevation of 550 K above the rotational temperature () of 500 K. After the plasma pulse, the characteristic relaxation time of T3 to strongly depends on the rotational temperature. By adjusting the duty cycle, the rotational temperature directly after the discharge is varied from 530 to 860 K, resulting in relaxation times between 0.4 and 0.1 ms. Equivalently, as the gas heats up during the plasma pulse, the elevation of T3 above decreases strongly.