IR Fingerprint Research Articles

A Rapid Method of Crude Oil Analysis Using FT-IR Spectroscopy

This study determines the viability of the use of Fourier Transform Infrared (FTIR) spectroscopy as a substitute to traditional petroleum geochemical methods for crude oil characterisation. IR spectra of Crude oil sample containing a mixture of both degraded (sample 151) and non-degraded (sample 145) oils at different concentrations were determined. The IR fingerprints agree with results obtained from GC analysis. Partial least square regression analysis was used to predict saturates for omitted mixtures (10 and 80% 151) and also saturates of five other samples (i.e. 145, 149, 172, H1 and AL10) within acceptable error limits. It therefore, follows, that although some improvements might still need to be made, FTIR spectroscopy can indeed be a viable, simple, cheaper and faster technique of crude oil characterisation compared with the traditional fractionation methods.Keywords: FTIR-ATR spectroscopy; GC-MS; Partial least squares (PLSR). Rapid analysis.

Gas phase structures and charge localization in small aluminum oxide anions: Infrared photodissociation spectroscopy and electronic structure calculations.

We use cryogenic ion trap vibrational spectroscopy in combination with quantum chemical calculations to study the structure of mono- and dialuminum oxide anions. The infrared photodissociation spectra of D2-tagged AlO1-4 (-) and Al2O3-6 (-) are measured in the region from 400 to 1200 cm(-1). Structures are assigned based on a comparison to simulated harmonic and anharmonic IR spectra derived from electronic structure calculations. The monoaluminum anions contain an even number of electrons and exhibit an electronic closed-shell ground state. The Al2O3-6 (-) anions are oxygen-centered radicals. As a result of a delicate balance between localization and delocalization of the unpaired electron, only the BHLYP functional is able to qualitatively describe the observed IR spectra of all species with the exception of AlO3 (-). Terminal Al-O stretching modes are found between 1140 and 960 cm(-1). Superoxo and peroxo stretching modes are found at higher (1120-1010 cm(-1)) and lower energies (850-570 cm(-1)), respectively. Four modes in-between 910 and 530 cm(-1) represent the IR fingerprint of the common structural motif of dialuminum oxide anions, an asymmetric four-member Al-(O)2-Al ring.

Astro-organometallics of Fe, Co, Ni: Stability, IR fingerprints and possible locations

A set of transition metal (TM) compounds defined as [TMnLmAro]; where L and Ar are ligand molecules; are proposed to have astrochemical relevance. Their chemical nature, stability, spectral footprints and possible localizations are developed. To select a representative [TMnLmAro] ensemble three selection rules are conceived: (a) TM cosmic abundances; (b) L, Ar cosmic abundances and (c) L, Ar reactivity toward the TM. The resulting classes of compounds are: (I) [TMLn]; (II) [TMnLm]; (III) [TMAr], [TMnAr] and (IV) [LnTMAr], with TM=Fe, Co, Ni; Ar=benzene (Bz), coronene (Cor), circumcoronene (CCor) as model compounds for the aromatic interactions and L=CO, H2O, CN−, H2. Bond dissociation energies (D) for each class are listed from experimental data (when possible) or calculated by DFT methods (BP/TZVP//BP/SVP level of theory). The D of many [TMnLmAro] do compare with stable bonds like CC or CC supporting their “on-paper” existence. The IR is proposed as the most promising and informing spectral region where to search/analyze the [TMnLmAro] characterized by a series of “fingerprints”. Finally the fact that [TMnLmAro] are mostly organometallic in nature suggest their presence in detectable amount where a carbon and water rich chemistry is present.

Protonation induces base rotation of purine nucleotides pdGuo and pGuo.

Infrared multiple photon dissociation (IRMPD) action spectra of the protonated forms of 2'-deoxyguanosine-5'-monophosphate and guanosine-5'-monophosphate, [pdGuo+H](+) and [pGuo+H](+), are measured over the IR fingerprint and hydrogen-stretching regions using the FELIX free electron laser and an OPO/OPA laser system. Electronic structure calculations are performed to generate low-energy conformations of [pdGuo+H](+) and [pGuo+H](+) and determine their relative stabilities at the B3LYP/6-311+G(2d,2p)//B3LYP/6-311+G(d,p) and MP2(full)/6-311+G(2d,2p)//B3LYP/6-311+G(d,p) levels of theory. Comparative analyses of the measured IRMPD action spectra and B3LYP/6-311+G(d,p) linear IR spectra computed for the low-energy conformers are performed to determine the most favorable site of protonation and the conformers present in the experiments. These comparisons and the computed energetics find that N7 protonation is considerably preferred over O6 and N3, and the N7 protonated ground-state conformers of [pdGuo+H](+) and [pGuo+H](+) are populated in the experiments. The 2'-hydroxyl substituent does not significantly impact the stable low-energy conformers of [pdGuo+H](+)vs. those of [pGuo+H](+). The effect of the 2'-hydroxyl substituent is primarily reflected in the relative intensities of the measured IRMPD bands, as the IRMPD profiles of [pdGuo+H](+) and [pGuo+H](+) are quite similar. Comparisons to previous IRMPD spectroscopy investigations of the protonated forms of the guanine nucleosides, [dGuo+H](+) and [Guo+H](+), and deprotonated forms of the guanine nucleotides, [pdGuo-H](-) and [pGuo-H](-), provide insight into the effects of the phosphate moiety and protonation on the conformational features of the nucleobase and sugar moieties. Protonation is found to induce base rotation of the guanine residue to an anti orientation vs. the syn orientation found for the deprotonated forms of the guanine nucleotides.

Analysis of Chuanxiong Rhizoma and its active components by Fourier transform infrared spectroscopy combined with two-dimensional correlation infrared spectroscopy

As complicated mixture systems, active components of Chuanxiong Rhizoma are very difficult to identify and discriminate. In this paper, the macroscopic IR fingerprint method including Fourier transform infrared spectroscopy (FT-IR), the second derivative infrared spectroscopy (SD-IR) and two-dimensional correlation infrared spectroscopy (2DCOS-IR), was applied to study and identify Chuanxiong raw materials and its different segmented production of HPD-100 macroporous resin. Chuanxiong Rhizoma is rich in sucrose. In the FT-IR spectra, water eluate is more similar to sucrose than the powder and the decoction. Their second derivative spectra amplified the differences and revealed the potentially characteristic IR absorption bands and combined with the correlation coefficient, concluding that 50% ethanol eluate had more ligustilide than other eluates. Finally, it can be found from 2DCOS-IR spectra that proteins were extracted by ethanol from Chuanxiong decoction by HPD-100 macroporous resin. It was demonstrated that the above three-step infrared spectroscopy could be applicable for quick, non-destructive and effective analysis and identification of very complicated and similar mixture systems of traditional Chinese medicines.

Application of mid-infrared spectroscopy in analyzing different segmented production of Angelica by AB-8 macroporous resin

As complicated mixture systems, chemical components of Angelica are very difficult to identify and discriminate, so as not to control its quality effectively. In recent years, Mid-infrared spectroscopy has been innovatively employed to identify and assess the quality of Traditional Chinese medicine (TCM) products. In this paper, the macroscopic IR fingerprint method including Fourier transform infrared spectroscopy (FT-IR), the second derivative infrared spectroscopy (SD-IR) and two-dimensional correlation infrared spectroscopy (2D-IR), are applied to study and identify Angelica raw material, the decoction and different segmented production of AB-8 macroporous resin. FT-IR spectrum indicates that Angelica raw material is rich in sucrose and the correlation coefficient is 0.8465. The decoction of Angelica contains varieties of polysaccharides components and the content is gradually decreased with increasing concentration of ethanol. In addition, the decoction of Angelica contains a certain amount of protein components and 50% ethanol eluate has more protein than other eluates. Their second derivative spectra amplify the differences and reveal the potentially characteristic IR absorption bands, then we conclude that the decoction of Angelica contains a certain amount of ferulic acid and ligustilide. And 30% ethanol eluate, 50% ethanol eluate and 70% ethanol eluate are similar to ligustilide. Further, 2D-IR spectra enhance the spectral resolution and obtain much new information for discriminating the similar complicated samples. It is demonstrated that the above three-step infrared spectroscopy could be applicable for effective, visual and accurate analysis and identification of very complicated and similar mixture systems of traditional Chinese medicines.

Multi-resident identification using device-free IR and RF fingerprinting.

Remote monitoring of health and mobility is critical in the support of aging-in-place for seniors. However, it is challenging to passively monitor individuals in multi-resident homes. In this paper we present a new method for the identification of individuals using simple wall-mounted radio frequency (RF) transceivers and IR sensors with fingerprinting techniques. The approach is passive or device-free in that it does not require the person being identified to wear any transmitting device Classification is achieved using features derived from measuring the disruption of RF received signal strength (RSS) among 4 transceivers positioned across either a hallway or doorframe. Three IR sensors provide timing information. Results are given for 3 test subjects (1 female, 2 males). The approach achieves over 98% classification accuracy in distinguishing the female from the male subjects and over 83% in distinguishing between the males using a Gaussian Mixture Model for classification. More than 2300 labeled examples per subject were used for training. When the training data is reduced to less than 140 examples per subject, 96% and 82% classification accuracy is still achieved respectively.

Gas-phase conformations and energetics of protonated 2'-deoxyadenosine and adenosine: IRMPD action spectroscopy and theoretical studies.

The gas-phase conformations of protonated 2'-deoxyadenosine, [dAdo+H](+), and its RNA analogue protonated adenosine, [Ado+H](+), generated upon electrospray ionization are examined using infrared multiple photon dissociation (IRMPD) action spectroscopy techniques and supported by complementary theoretical electronic structure calculations. IRMPD action spectra are measured over the IR fingerprint region using the FELIX free-electron laser and the hydrogen-stretching region using an optical parametric oscillator/amplifier laser system. The measured IRMPD spectra are compared to linear IR spectra predicted for the stable low-energy conformations of [dAdo+H](+) and [Ado+H](+) computed at the B3LYP/6-311+G(d,p) level of theory to determine the preferred site of protonation and to identify the structures populated in the experiments. N3 is found to be the most favorable site of protonation for both [dAdo+H](+) and [Ado+H](+), whereas conformers protonated at the N1 and N7 positions are much less stable by >25 kJ/mol. The 2'-hydroxyl substituent of Ado does not lead to a significant change in the structure of the ground-state conformer of [Ado+H](+) as compared to that of [dAdo+H](+), except that it provides additional stabilization via the formation of an O2'H···O3' hydrogen bond. Therefore, [dAdo+H](+) and [Ado+H](+) exhibit highly parallel IRMPD spectral features in both the fingerprint and hydrogen-stretching regions. However, the additional 2'-hydroxyl substituent markedly affects the IRMPD yield of the measured IR bands. The spectral signatures in the hydrogen-stretching region provide complementary information to that of the fingerprint region and enable facile differentiation of the conformers that arise from different protonation sites. In spite of the relative gas-phase stabilities of the N3 and N1 protonated conformers, present results suggest that both are accessed in the experiments and contribute to the measured IRMPD spectrum, indicating that the relative stabilities in solution also influence the populations generated by electrospray ionization.

Diverse mixtures of 2,4-dihydroxy tautomers and O4 protonated conformers of uridine and 2'-deoxyuridine coexist in the gas phase.

The gas-phase conformations of protonated uridine, [Urd+H](+), and its modified form, protonated 2'-deoxyuridine, [dUrd+H](+), generated by electrospray ionization are investigated using infrared multiple photon dissociation (IRMPD) action spectroscopy techniques. IRMPD action spectra of [Urd+H](+) and [dUrd+H](+) are measured over the IR fingerprint and hydrogen-stretching regions. [Urd+H](+) and [dUrd+H](+) exhibit very similar IRMPD spectral profiles. However, the IRMPD yields of [Urd+H](+) exceed those of [dUrd+H](+) in both the IR fingerprint and hydrogen-stretching regions. The measured spectra are compared to the linear IR spectra predicted for the stable low-energy structures of these species computed at the B3LYP/6-311+G(d,p) level of theory to determine the tautomeric conformations populated by electrospray ionization. Both B3LYP and MP2 methods find O4 and O2 protonated canonical as well as 2,4-dihydroxy tautomers among the stable low-energy structures of [Urd+H](+) and [dUrd+H](+). Comparison between the measured IRMPD and calculated linear IR spectra suggests that these species exist in their ring-closed forms and that both 2,4-dihydroxy tautomers as well as O4 protonated canonical conformers coexist in the population generated by electrospray ionization for both [Urd+H](+) and [dUrd+H](+). The 2'-deoxy modification of [dUrd+H](+) reduces the variety of 2,4-dihydroxy tautomers populated in the experiments vs. those of [Urd+H](+).

Multiple-fingerprint analysis for investigating quality control of Flammulina velutipes fruiting body polysaccharides.

Quality control issues overshadow potential health benefits of the edible mushroom Flammulina velutipes, with the detection and isolation of polysaccharides posing particular problems. In this study, multiple-fingerprint analysis was performed using chemometrics to assess polysaccharide quality and antioxidant activity of F. velutipes fruiting bodies from different sources. The authentic source exhibited differences in both oxygen radical absorbance capacity and ferric reducing antioxidant power from foreign sources. IR spectroscopic/HPLC fingerprints of polysaccharide extracts from the authentic source were established and applied to assess the polysaccharide quality of foreign sources. Analysis of IR fingerprints using Pearson correlation coefficient gave correlation coefficient r values of 0.788 and 0.828 for two foreign sources, respectively, indicating distinctness from the authentic source. Analysis of HPLC fingerprints using the supervised method by Traditional Chinese Medicine could not discriminate between sources (r > 0.9), but principal component analysis of IR and HPLC fingerprints distinguished the foreign sources.

Rearrangement chemistry of an ions probed by IR spectroscopy

The structure and the dynamics of the isomerization of an ions, which are observed upon low-energy collision induced dissociation of protonated peptides in tandem mass spectrometry (MS/MS), are investigated using a combination of gas phase infrared spectroscopy and theory. IR spectra in the fingerprint region are discussed, but a particular emphasis is given to the NH stretching region which turns out to be highly structurally diagnostic. Overall, theory and infrared spectroscopy provide compelling evidence that an ions undergo cyclisation and/or rearrangement reactions. In the cases of the a2 and a3 ions of oligoglycine, the analysis of the NH stretching region is fully consistent with our previous conclusions based on the IR fingerprint spectra. In the case of the a4 ions of oligoglycine, a band observed near 3550cm−1 provides a clear-cut signature of the permuted imine–amide structure, thus allowing for a better structural assignment. The dynamics of the rearrangement chemistry of the imine–amide structure is discussed in details, and a critical discussion on the influence of the experimental CID conditions is proposed in the case of the YG a2 ion.

Preliminary study on pharmacodynamic evaluation method of Houpo formula particles

To discuss the feasibility of the pharmacodynamic evaluation method for traditional Chinese medicine (TCM) formula particles, with traditional decoction for reference and the intervention of Magnoliae Officinalis Cortex in rats with ulcerative colitis (UC). First of all, the similarity of traditional Magnoliae Officinalis Cortex decoction and formula particles of different manufacturers was defined by using the IR fingerprint. The UC rat model was established and given Houpo formula particles of different doses and manufacturers, with the decoction for reference, in order to observe disease activity index (DAI), colon mucosa damage index (CMDI), pathologic changes, nitric oxide (NO), endothdin (ET), substance P, vasoactive intestinal peptide (VIP). Their intervention effects on UC rats were compared to study the difference between Sanjiu and Tianjiang Houpo formula particles, in order to demonstrate the feasibility of the pharmacodynamic evaluation method for Houpo formula particles. According to the results, Houpo formula particles showed similar pharmacodynamic actions with the traditional decoction. The pharmacodynamic comparison of Houpo formula particles of different manufacturers showed no statistical significance. The experiment showed that on the basis of the TCM compounds, a prescription dismantlement study was conducted to define target points of various drugs. The traditional decoction was selected for reference in the comparison of corresponding formula particles for their pharmacodynamic equivalence. This method could avoid controversies about single or combined boiling of formula particles, and give objective comments on the pharmacodynamic effect of the formula particles. The method is proved to be feasible.

Multi-step infrared macro-fingerprint features of ethanol extracts from different Cistanche species in China combined with HPLC fingerprint

The genus Cistanche generally has four species in China, including C. deserticola (CD), C. tubulosa(CT), C. salsa(CS) andC. sinensis(CSN), among which CD and CT are official herbal sources of Cistanche Herba (CH). To clarify the sources of CH and ensure the clinical efficacy and safety, a multi-step IR macro-fingerprint method was developed to analyze and evaluate the ethanol extracts of the four species. Through this method, the four species were distinctively distinguished, and the main active components phenylethanoid glycosides (PhGs) were estimated rapidly according to the fingerprint features in the original IR spectra, second derivative spectra, correlation coefficients and 2D-IR correlation spectra. The exclusive IR fingerprints in the spectra including the positions, shapes and numbers of peaks indicated that constitutes of CD were the most abundant, and CT had the highest level of PhGs. The results deduced by some macroscopic features in IR fingerprint were in agreement with the HPLC fingerprint of PhGs from the four species, but it should be noted that the IR provided more chemical information than HPLC. In conclusion, with the advantages of high resolution, cost effective and speediness, the macroscopic IR fingerprint method should be a promising analytical technique for discriminating extremely similar herbal medicine, monitoring and tracing the constituents of different extracts and even for quality control of the complex systems such as TCM.

Rapid discrimination of three Uighur medicine of Eremurus by FT-IR combined with 2DCOS-IR

As complicated mixture systems, traditional Chinese medicines (TCMs) are difficult to be identified and discriminated, especially for the drug samples originated from the same source. In this study, a tri-step infrared spectroscopy method, i.e., conventional infrared spectroscopy (FT-IR) combined with second derivatives spectra and two-dimensional correlation infrared spectroscopy (2DCOS-IR), was employed to study and identify three Uighur drugs of Eremurus in Xinjiang, i.e. Eremurus altaicus (Pall.) Stev (AET), E. inderiensis (M.Bieb.)Regel(CB), E. anisopterus (Kar.et Kir.) Regel(YC). It was founded that the conventional IR spectra of the three species Eremurus were very similar based on the peak positions and shapes, indicating that the three had similar chemical profiles. On the basis of the different IR spectra of reference compounds and microscopic identification, the roots of YC, CB and AET all have comparable amount of calcium oxalate. The second derivative spectra of Eremurus enhanced the spectral resolution and amplified the small differences, especially at about 1468cm−1, 1454cm−1, and 1164cm−1, and subsequently provided some dissimilarity in their calcium oxalate content. AET has relatively higher content of calcium oxalate but the lower content of anthraquinones. Moreover, the 2D-IR spectra revealed tiny differences among the three species by providing dynamic structural information of their chemical components in a more direct and visual way. The differences embodied mainly on the intensity of the auto-peaks at 971cm−1, 1008cm−1, 1468cm−1 and 1578cm−1. As a result, it was demonstrated that the macroscopic IR fingerprint method could discriminate the three similar Uighur drugs, YC, CB and AET.

Intimate Binding Mechanism and Structure of Trigonal Nickel(I) Monocarbonyl Adducts in ZSM-5 Zeolite—Spectroscopic Continuous Wave EPR, HYSCORE, and IR Studies Refined with DFT Quantification of Disentangled Electron and Spin Density Redistributions along σ and π Channels

Interaction of tetracoordinated nickel(I) centers generated inside the channels of ZSM-5 zeolite with carbon monoxide ((12,13)CO, pCO < 1 Torr) led to the formation of T-shaped, top-on monocarbonyl adducts with a unique trigonal nickel core, supported by two oxygen donor ligands. The mechanism of the formation of the {Ni(I)-CO}ZSM-5 species was accounted for by a quantitative molecular orbital correlation diagram of CO ligation. Detailed electronic and magnetic structure of this adduct was obtained from comprehensive DFT calculations, validated by quantitative reproduction of its continuous wave electron paramagnetic resonance (CW-EPR), hyperfine sublevel correlation (HYSCORE), and IR fingerprints, using relativistic Pauli and ZORA-SOMF/B3LYP methods. Molecular analysis of the stretching frequency, νCO = 2109 cm(-1), g and A((13)C) tensors (g(xx) = 2.018, g(yy) = 2.380, g(zz) = 2.436, A(xx) = +1.0 ± 0.3 MHz, A(yy) = -3.6 ± 0.9 MHz, A(zz) = -1.6 ± 0.3 MHz) and Q((27)Al) parameters (e(2)Qq/h = -13 MHz and η = 0.8) supported by quantum chemical modeling revealed that the Ni-CO bond results from the π overlap between the low-laying π(2p) CO states with the 3d(xz) and 3d(yz) orbitals, with a small σ contribution due to the overlap of σ(2p+2s) orbital and a protruding lobe of the in-plane 3d(xz) orbital. Two types of orbital channels (associated with the σ and π overlap) of the electron and spin density flows within the {Ni(I)-CO} unit were identified. A bathochromic shift of the νCO stretching vibration was accounted for by resolving quantitatively the separate contributions due to the σ donation and π back-donation, whereas the (13)C hyperfine coupling was rationalized by incongruent α and β spin flows via the σ and π channels. As a result the very nature of the carbon-metal bond in the Ni(I)-CO adduct and the molecular backbone of the corresponding spectroscopic parameters were revealed with unprecedented accuracy.

Steady-state one-dimensional and transient two-dimensional infrared spectroscopies reveal multiple aggregated species of amyloid &amp;beta; fragment

Fourier transform infrared (FTIR) and femtosecond two-dimensional infrared (2D IR) methods were used to monitor the aggregation process of amyloid-beta (Aβ) fragment (amino acid residue 1-25, Aβ1-25) under acidic condition, using the amide-I mode located on peptide backbone as structural probe. The conformation of Aβ1-25 peptide and its structural dynamics during aggregation were examined. The results showed that Aβ1-25 formed a mixture of structures with different aggregation degrees, and random coil as well. The initial and final states both exhibit measurable IR signatures. In particular, the 2D IR fingerprints were reflected in the inhomogeneous and homogeneous linewidths, nodal line orientation, and the distributions of the off-diagonal peaks. Based on these results, dynamical interactions between amide units, between peptide backbones, and solvent molecules were discussed.

Direct discrimination of different plant populations and study on temperature effects by Fourier transform infrared spectroscopy

Fourier transform infrared spectroscopy was used to characterise highland and lowland populations of Polygonum minus Huds. grown in different controlled environments. A thermal perturbation technique of two- dimensional correlation infrared spectroscopy (2D-IR) cor- relation spectra was applied to establish differences between the populations. The absorption peaks at 3,480 cm -1 (hydroxyl group), 2,927 cm -1 (methyl group), 1,623 cm -1 (carbonyl group), and 1,068 cm -1 (C-O group) were par- ticularly powerful in separating the populations. These peaks, which indicate the presence of carbohydrate, terp- enes, amide and flavonoids were more intense for the high- land populations than lowland populations, and increased in environments with a higher temperature. Wavenumbers (1,634, 669 cm -1 ) and (1,634, 1,555 cm -1 ) in the 2D-IR correlation spectra provided fingerprint signals to differen- tiate plants grown at different temperatures. This study demonstrates that IR fingerprinting, which combines mid-IR spectra and 2D-IR correlation spectra, can directly discrim- inate different populations of P. minus and the effects of temperature.

Protonation Preferentially Stabilizes Minor Tautomers of the Halouracils: IRMPD Action Spectroscopy and Theoretical Studies

Tautomerization induced by protonation of halouracils may increase their efficacy as anti-cancer drugs by altering their reactivity and hydrogen bonding characteristics, potentially inducing errors during DNA and RNA replication. The gas-phase structures of protonated complexes of five halouracils, including 5-fluorouracil, 5-chlorouracil, 5-bromouracil, 5-iodouracil, and 6-chlorouracil are examined via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical electronic structure calculations. IRMPD action spectra were measured for each complex in the IR fingerprint region extending from ~1000 to 1900 cm(-1) using the free electron laser (FELIX). Correlations are made between the measured IRMPD action spectra and the linear IR spectra for the stable low-energy tautomeric conformations computed at the B3LYP/6-311+G(2d,2p)//B3LYP/6-31G* level of theory. Absence of an intense band(s) in the IRMPD spectrum arising from the carbonyl stretch(es) that are expected to appear near 1825 cm(-1) provides evidence that protonation induces tautomerization and preferentially stabilizes alternative, noncanonical tautomers of these halouracils where both keto functionalities are converted to hydroxyl groups upon binding of a proton. The weak, but measurable absorption, which does occur for these systems near 1835 cm(-1) suggests that in addition to the ground-state conformer, very minor populations of excited, low-energy conformers that contain keto functionalities are also present in these experiments.

Study on Analysis and Assessment of &lt;i&gt;Acanthopanax senticosus&lt;/i&gt; from China and Korea with FT-IR

To get the IR spectrums of Acanthopanax senticosus (AS) from china and korea areas, and to find out the characters of IR spectrums through the content of different chemical constituents, provide a fast and effective analysis method monitor the inherent qualities of traditional Chinese medicine-AS. Fourier transform infrared spectroscopy (FT-IR) was applied to detect sample of AS from china and korea areas. This study showed that the IR spectra of AS from china and korea areas have their unique IR fingerprint features. The content of syringin and calcium oxalate in AS from china is significantly higher AS from korea. So FT-IR is a very quick, effective and well repetitive method for monitoring and distinguishing the traditional Chinese medicine.

Inside Cover: Infrared Spectrum and Structure of the Adamantane Cation: Direct Evidence for Jahn-Teller Distortion (Angew. Chem. Int. Ed. 20/2012)

The gas-phase infrared spectrum of the adamantane radical cation, C10H16+, provides the first spectroscopic characterization of the geometric and electronic structure of this cycloalkane carbocation and direct evidence for the Jahn–Teller distortion in the 2A1 ground electronic state. In their Communication on page 4925 ff., O. Dopfer et al. show that the characteristic IR fingerprint may be used for the identification of C10H16+ in hydrocarbon plasmas, including the interstellar medium.