Fourier Transform Infrared Absorption Spectroscopy Research Articles

Spectroscopic, thermogravimetric studies and DFT calculations of pentoxyverine citrate ion-pairs with sulfonephthalein dyes

Pentoxyverine citrate (PEN-citrate) ion-pairs with six sulfonephthaleins acid dyes; bromocresol green (BCG), bromophenol blue (BPB), bromothymol blue (BTB), bromocresol purple (BCP), bromochlorophenol blue (BChPB) and bromoxylenol blue (BXB) have been prepared. A structural characterization and elucidation of these ion-pairs applying UV–visible spectroscopy, Fourier transform infrared absorption spectroscopy (FTIR), nuclear magnetic resonance (1H NMR) and mass spectrometry have been carried out. Moreover, the spectral characteristics; oscillator strengths, transition dipole moments, transition energy and resonance energy of the ion-pairs have been calculated. Further characterization of the prepared compounds was done with the aid of thermogravimetric analysis for the determination of their thermal stability. The energy of activation (Ea) for the degradation of the prepared ion-pairs and some of their thermodynamic properties such as activation enthalpy (ΔH), activation entropy (ΔS) and activation free energy (ΔG) of each decomposition step using Horowitz-Metzger method have been calculated. The binding nature of a representative ion pair has been explored at a molecular level by performing quantum chemical calculations. Here, DFT based full geometry optimization has been carried out for PEN, neutral and charged (specifically anion) forms of bromophenol blue (BPB and BPB−), and the PEN–(BPB−) ion pair. The results indicated that this ion pair exhibits strong-to-medium hydrogen bond between the BPB sulfonate group and the PEN amino group with distance of 1.58 Å. Harmonic vibrations of BPB, PEN and PEN–(BPB−) ion pair have been calculated and the corresponding calculated spectra have been compared with the experimental Infrared spectra. Moreover, the UV–visible spectra and their corresponding excited states and electronic transitions for PEN–(BPB−) ion-pair have been investigated in DMSO.

Electrochemical properties of nickel phthalocyanine: The effect of thin film morphology tuned by deposition techniques

The electrical and optical properties of thin films can be modulated by its supramolecular arrangement being this latter closely related to the fabrication method. Here, we are exploiting the impact of deposition techniques of nickel phthalocyanine (NiPc) and tetrasulfonated nickel phthalocyanine (NiTsPc) thin films on their supramolecular arrangement. Deposition techniques as Langmuir-Schaffer (LS), Langmuir-Blodgett (LB), physical vapor deposition (PVD), dipping- and spray-Layer-by-Layer (LbL) were applied for fabrication of the thin films. Linear growth was observed for all films indicating control of the amount of NiPc or NiTsPc deposited in each technique at nm scale. Fourier-transform infrared absorption spectroscopy (FTIR) and micro-Raman scattering confirmed the chemical stability of NiPc and NiTsPc concerning the deposition technique (water or heat). Besides, FTIR and X-ray diffraction data suggested that all thin films present isotropy in terms of molecular organization, with a predominance of the crystalline α-phase in the case of PVD, LB, and LS films. Atomic force microscopy images revealed irregularities at the surface for all thin film with the roughness/thickness ratio being 4.5% for PVD, 9% for both LB and LS films, and 18 and 35% for spray- and dipping-LbL films, respectively. The electrochemical behavior in both inert electrolyte and dopamine (DA) solution was directly dependent on the film morphology (molecular aggregates and surface roughness). The increase of the roughness in relation to thickness promoted films better electrochemical responses to DA oxidation. The dipping-LbL films showed the smaller potential of DA oxidation (0.114 V), even compared to the bare substrate (0.133 V). The deposition technique showed to be an suitable tool to tune the supramolecular arrangement of phthalocyanine forming thin films, which improve and/or change the electrochemical properties of the device.

Determination of nitrites and nitrates in plasma‐activated deionized water by microchip capillary electrophoresis

AbstractIn this work, we present the application of a fast and sensitive microanalytical method, microchip capillary electrophoresis (MCE), for the determination of NO2− and NO3− ions in deionized water treated by atmospheric pressure plasma jet (APPJ). The MCE technique consisted of an online combination of isotachophoresis with zone electrophoresis, both performed on the microchip. The argon plasma has been characterized by optical emission spectroscopy (OES) and Fourier transform infrared spectroscopy (FTIR). OES confirmed the presence of argon excited species (Ar I) emission (4p → 4s) lines, N2 emission bands (second positive system C3Πu → B3Πg), and OH band (A2∑+ → X2Π Δv = 0), as well as the presence of NO and excited NO2. The presence of NO2 molecules was also confirmed by FTIR absorption spectroscopy. The performance of the developed MCE method was evaluated for linearity, limit of detection, limit of quantitation, precision, and accuracy, and the concentration of NO2− and NO3− in the water as a function of the water treatment time was monitored.

Insight into the isotherm modelling, kinetic and thermodynamic exploration of iron adsorption from aqueous media by activated carbon developed from Limonia acidissima shell

The present research article investigated the adsorption of iron ions from aqueous solution using activated carbon as an adsorbent prepared from Limonia acidissima shell by chemical activation technique. Box-Behnken design (BBD) of Response surface methodology (RSM), was employed to optimize the experimental conditions for the preparation of activated carbon. The carbon yield and iodine no. approached 42.74% and 959.42 mg/g under the optimal conditions of IR (23.44%), activation time (39.60 min), and carbonization temperature (418.74 °C). The BET analysis presented that the optimized adsorbent exhibited a high surface area of 1863.49 m2/g. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Fourier transform infrared absorption spectroscopy (FTIR), Transmission electron microscopy (TEM) and determining the point of zero charge (pHzpc) were employed to characterize the adsorbent. The removal efficacy of the adsorbent for total Fe ion was studied in batch mode as a function of pH, contact time, initial concentration, adsorbent dosage, and temperature. The findings indicated that the adsorption procedure could be well-defined by Langmuir isotherm and pseudo-second-order kinetic model because of the high coefficient of determination (R2) value is 0.99, which is almost close to 1. The maximum adsorption capacity of total Fe ion by optimized activated carbon was determined as 48.5 mg/g. The mean free energy calculated from D-R isotherm implied that the physisorption is the dominant process in adsorption. The thermodynamic calculations suggested the spontaneous nature of the sorption process, along with the exothermic characteristics. According to XPS results, most of the metal ions adsorbed on the carbon surface primarily existed as Fe3+(85.26%) with only (14.38%) remaining as Fe2+. Based on the outcomes of sorption studies, electrostatic interaction and surface complexation are the probable mechanisms for total Fe ion adsorption.

Sintesis Nanopartikel Perak dan Pengaruh Penambahan Asam p-Kumarat Untuk Aplikasi Deteksi Melamin

Biosynthesis of silver nanoparticles (AgNPs) using mangosteen bark extract, modification and its application in detecting melamine has conducted. This research aimed to synthesize AgNPs via bio-reduction method using mangosteen bark extract followed by modification with p-coumaric acid (APK), and evaluating its application detecting melamine. The AgNPs were characterized through ultraviolet-visible absorption spectroscopy (UV-Vis), Fourier transform infrared absorption spectroscopy (FTIR), and X-ray diffraction (XRD). Observation suggested that an increase of incubation time had affected its surface Plasmon resonance trend. Observation of functional group by FTIR showed that carbonyl group (1707 cm-1) suspected from hydroxyl group (3414 cm-1). Further analysis of crystallite via XRD suggested that nanoparticle size at 30 nm estimated using Debye-Scherer, within the form of unit cells is cubic. Modified AgNPs showed an interaction between APK and particle surface through C=C alkenes (1598 cm-1) and aromatics (1672 cm-1), =C-H aromatic (3070 cm-1), aliphatic C-H (2501 cm-1), C-O (1107 cm-1) and C=O carboxylate (1774 cm-1). The performance of product as melamine detector suggested that the AgNPs-APK had detected melamine in range of concentration from 0.1 to 1000 ppm.

Sintesis Nanopartikel Perak dan Pengaruh Penambahan Asam p-Kumarat Untuk Aplikasi Deteksi Melamin

Biosynthesis of silver nanoparticles (AgNPs) using mangosteen bark extract, modification and its application in detecting melamine has conducted. This research aimed to synthesize AgNPs via bio-reduction method using mangosteen bark extract followed by modification with p-coumaric acid (APK), and evaluating its application detecting melamine. The AgNPs were characterized through ultraviolet-visible absorption spectroscopy (UV-Vis), Fourier transform infrared absorption spectroscopy (FTIR), and X-ray diffraction (XRD). Observation suggested that an increase of incubation time had affected its surface Plasmon resonance trend. Observation of functional group by FTIR showed that carbonyl group (1707 cm-1) suspected from hydroxyl group (3414 cm-1). Further analysis of crystallite via XRD suggested that nanoparticle size at 30 nm estimated using Debye-Scherer, within the form of unit cells is cubic. Modified AgNPs showed an interaction between APK and particle surface through C=C alkenes (1598 cm-1) and aromatics (1672 cm-1), =C-H aromatic (3070 cm-1), aliphatic C-H (2501 cm-1), C-O (1107 cm-1) and C=O carboxylate (1774 cm-1). The performance of product as melamine detector suggested that the AgNPs-APK had detected melamine in range of concentration from 0.1 to 1000 ppm.

Study on SOI structure irradiated by electron and annealled treatment using C–V, FTIR and PL

Abstract In this work, the commercial silicon on insulator (SOI) wafers irradiated by 0.5 MeV electrons with a fluence of 1.5⨯1014 ~ 2.3⨯1015 cm−2 and annealed among 150 °C and 300 °C have been studied in detail. The performances of SOI samples are investigated by Geant4, Capacitance - Voltage (C–V), Fourier Transform Infrared Spectroscopy (FTIR) and Photoluminescence (PL). The C–V measurements indicate that capacitance decrease under positive voltage bias with increasing fluence. The free carrier concentration decreases with increasing fluence and increases with rising annealing temperature, which can be attributed to the traps induced by electron irradiation on Si/SiO2 interface. There is only the presence of Si–O bonding from the FTIR absorption peaks exhibiting at ~940, ~960, and ~1170 cm−1. The relative intensity of three peaks become weaker with higher irradiation fluence and annealing under 150 °C, which is in good agreement with the Monte Carlo numerical simulation (Geant4). The PL spectra reveals that there is a strong photoluminescence emission at about 420 nm (2.95 eV), which is ascribed to the radiative recombination centers in SiO2 layer. In addition, weaker peaks of PL emission at 720 nm (1.72 eV) and 835 nm (1.49 eV) are also discussed in this paper.

Antiaging Property and Mechanism of Phase‐Change Asphalt with PEG as an Additive

In this study, phase‐change asphalt was prepared with polyethylene glycol (PEG‐1000) as a modifier. The short‐ and long‐term antiaging performances were characterized by rolling‐thin‐film‐oven (RTFOT) and pressure‐aging vessel (PAV) tests, respectively. The functional groups and “bee structures” of PEG‐modified asphalt and base asphalt were characterized by Fourier transform infrared absorption spectroscopy (FTIR) and atomic force microscopy (AFM). The research results indicate that the additive of PEG can improve the high‐temperature, temperature sensitivity, and the antiaging properties of asphalt. The FTIR reveals that only physical blending and no chemical reaction occurs between PEG and asphalt. AFM topography indicates that smaller “bee structures” appear on the surface of PEG‐modified asphalt and these structures do not change during aging.

African black velvet tamarind (Dialium guineense) as a green adsorbent for groundwater remediation

Process shells of black velvet tamarind fruits was investigated as an adsorbent for the potential removal of the pollutant heavy metal ions of Fe, Cr, Pb, Mn and Zn in well water samples collected from six different locations in Enugu Metropolis, Eastern Nigeria. Fourier Transform Infra-Red Spectroscopy absorption bands characteristic of stretching, scissoring and bending vibrations of - O-H groups of alcohols (R-OH) and phenols (Ph-OH), Sp3 (–C-H) of an oxygen bonded carbon atom, –C-O-C- bond and Sp2 (---C==C—H) carbons in a ring structure were seen between 3400 to 3200 cm-1, 1438 to 1371 cm-1, 2922/2851 cm-1 and 1155/1028 cm-1 as well as the 1509 cm-1 in the infra-red region of the electromagnetic spectrum in the infra-red absorption spectrum of processed black velvet tamarind fruit shells. Metal ion analysis was carried out by Flame Atomic Absorption Spectroscopy. The results showed that the adsorbent removed 40.50 to 63.30, 33.33 to 52.63, 26.23 to 48.05 and 15.00 to 37.84% respectively of Fe, Zn, Cr and Mn in the well water samples but was ineffective in removing Pb. This demonstrates the usefulness of black velvet tamarind fruit shells in decontaminating heavy metal burdened water and suggests that the technique has potential to reclaim polluted water of such nature, ameliorate the problems of insufficient potable water and waste disposal as well as protect the environment from heavy metal pollution.

Osteogenic potential of human mesenchymal stem cells on eggshells-derived hydroxyapatite nanoparticles for tissue engineering.

Nanocrystalline hydroxyapatite (HAp) was synthesized from biowaste eggshells through sonication followed by the heat treatment. Calcium oxide as a precursor moiety for the synthesis of HAp was obtained through the heat treatment of eggshells at 900°C for 3 hr. The prepared HAp was characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). The appearance of the FTIR absorption peaks in between at 516-1031 and 3,636 cm-1 shows phosphate and hydroxyl groups in prepared HAp, respectively. The XRD-patterns indicate the formation of HAp started within 5 min of sonication. The SEM morphologies suggested that the synthesized HAp was highly crystalline and compact. We tested the elemental analysis of the synthesized HAp through X-ray fluorescence spectroscopy and inductively coupled plasma mass spectroscopy. The higher Ca/P ratio has observed in heat-treated HAp. These results show that heat treatment facilitates the formation of highly crystalline and compact HAp. Cytotoxicity and osteogenic potential of human mesenchymal stem cells (hMSCs) were also evaluated in the presence of HAp. No significant cytotoxicity was noted in the presence of HAp, suggested their biocompatibility. Enhanced osteogenesis of hMSCs occurred with HAp powder, confirming the feasibility in the treatment of osteogenesis. Thus, synthesized HAp has the potential to use a biomaterial in tissue engineering applications for bone tissues.

Experimental methods in chemical engineering: Fourier transform infrared spectroscopy—FTIR

AbstractWhen molecules absorb infrared radiation (IR), their vibrational mode—stretching and bending of the electric dipole—changes to an excited state. Functional groups in organic molecules absorb IR related to their characteristic vibrational modes. A Fourier transform infrared absorption (FTIR) analyzer measures the absorbed IR to identify molecular composition of surfaces, structural and geometric isomers, orientation in polymers and solutions, and quantify impurities. We describe the power of FTIR instruments and their basic operating principles, including the main experimental setups available: transmission, diffuse reflectance (DRIFTS), reflection adsorption infrared spectroscopy (RAIRS), and attenuated total reflection (ATR), including the recent advances related to time‐resolved and operando applications. In catalytic studies, FTIR spectroscopy has demonstrated its versatility over the last several decades to understand reaction mechanisms, measure gas phase composition, and identify active sites. Over 3000 articles include catalysis and FTIR as keywords but 50 000 articles per year mention IR. We generated a bibliometric map of keywords in articles that Web of Science indexed in 2016 and 2017. The map identified four broad clusters of research related to or applying FTIR: nano‐composites, composites, and mechanical properties; nano‐particles, degradation, graphene oxide, and photo‐catalysis; adsorption, aqueous solutions, and waste water; and drug delivery, silver and gold nano‐particles, green synthesis, and antibacterial activity. Together with a synopsis of the principals of IR spectroscopy and a review of the applications, we discuss uncertainties and limitations of the technique.

Post-depositional alterations of terrestrial and marine finds of Roman ceramics from Crikvenica production centre (NE Adriatic, Croatia) – A contribution towards chemometric classification

• Different post-depositional alterations of Roman ceramics from Crikvenica's pottery production were identified. • The effects of seawater, anoxic marine sediments and desalination are recognizable by multi-analytical methods. • Multivariate statistics on FT-IR spectra represent a suitable method for a first screening and identification of representative samples of each sub-group. • Ceramics excavated from the site of the workshop (local ceramics) can be used as a reference group for future classification studies of Roman ceramics from the Crikvenica production centre. Different post-depositional conditions and after-recovery treatments may provoke pronounced physicochemical alterations that can make archaeological ceramics’ classification and comparison difficult even when its provenance is known. The present study describes the differences in the chemical composition verified on sherds of Roman ceramics produced in Crikvenica (NE Adriatic, Croatia). Inductive coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), as well as Fourier transform infrared spectroscopy (FT-IR) were applied to characterise the chemical composition and post-depositional alterations in ceramics recovered onshore and underwater. Chemometrical treatment of ICP-MS results of elemental composition and FT-IR absorption bands was performed using univariate and multivariate statistical tools. Principal component analysis (PCA) led to clear distinction of several clusters of examined samples, i.e. samples from the mainland, samples from the sea bottom, and desalinated samples. All sherds that have undergone desalination represent a distinct sub-group by means of changes in the ratio of accumulated chemical elements. It was established that accumulation of Ca, Mg and Na and formation of salts such as FeS, Mg 6 Al 2 CO 3 (OH) 16 ·4(H 2 O), and CaCO 3 reflect post-depositional environments and post-recovery treatments in terms of desalination and specific marine underwater conditions (oxic and anoxic). Our results outlined a pattern of post-depositional alterations that could be applied in upcoming classification studies. Roman ceramics produced in Crikvenica and excavated from the workshop possess attributes of a reference group, revealing that Ho, Ce, La, Lu, Tb, Gd, Eu and Sm are the elements least susceptible to post-depositional alterations.

Synthesis of hydrophilic P(VDF-TrFE) chloride sensitive polymer films for fluorescence sensing

Hydrophilic lucigenine doped P(VDF-TrFE) based chloride sensitive films were prepared by three different methods. These include increased pore size and distribution, introduction of alumina nanoparticles and addition of amphiphilic copolymer. The properties of the films were characterized by scanning electron microscope (SEM), contact angle meter (CAM), fourier transform infrared absorption spectroscopy (FT-IR) and photoluminescence (PL) spectroscopy. The PL intensity of chloride sensitive films is chloride concentration-dependent and the evolution of the lucigenine related PL intensity as a function of the chloride concentration follows the Stern–Volmer equation. From all the results, addition of amphiphilic copolymer shows the best effect on the hydrophilic modification of the film as well as the chloride sensitivity, and one of the optimal linear calibration formula I0/I=1+15.069[Cl-] (R2=0.981) was obtained in the concentration range 0.02 M-0.10 M of a standard sodium chloride solution with a detection limit of 0.01M (S/N=3).

Analysis and Study of Characteristic FTIR Absorption Peaks in Hafnium Oxide Thin Films Deposited at Low-Temperature

In this study, hafnium oxide (HfO2) thin films were deposited by spin coating technique at different low deposition temperatures (150 °C, 200 °C and 250 °C). The properties of the films were measured by UV–visible spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) in the attenuated total reflectance mode. The films exhibit the typical absorption peaks related to Hf–O bonds. Interestingly, a trend is clearly observed between the transmittance, crystallographic planes and FTIR characteristic peaks as deposition temperature increases. Moreover, the fabrication and characterization of MOS capacitors is presented. The current–voltage and capacitance–voltage curves corroborated the trend observed in the characterization of the HfO2 films.

Positive Effects of Impregnation of Fe-oxide in Mesoporous Al-Oxides on the Decontamination of Dimethyl Methylphosphonate

Dimethyl methylphosphonate (DMMP) is an important simulant of organophosphates pesticides and chemical warfare nerve agents. Here, we investigated the catalytic decontamination of DMMP on Fe-oxide impregnated mesoporous Al2O3. Fe-oxide/Al2O3 sample was prepared via the temperature regulated chemical vapor deposition of Fe-oxide on mesoporous Al2O3 and post-annealing at 750 °C. The Fe-oxide/Al2O3 and bare Al2O3 samples were exposed to DMMP-containing dry air at room temperature to study the effects of Fe-oxide impregnation on the reactive adsorption of DMMP. The facilitation of DMMP degradation into CO2 and methanol at room temperature in the presence of nano-dispersed Fe-oxide was evidenced by gas-chromatograph and Fourier transform-infrared (FT-IR) absorption spectroscopy. In addition, temperature programmed oxidation (TPO) experiments and gas chromatography (Agilent, 6890) equipped with mass spectrometer (Agilent, 5973N) (GC/MS) analyses revealed that the minimum temperature that was required for total oxidation of DMMP into CO2 can also be lowered by Fe-oxide impregnation in mesoporous Al2O3.

Quantifying organic matter and functional groups in particulate matter filter samples from the southeastern United States – Part 1: Methods

Abstract. Comprehensive techniques to describe the organic composition of atmospheric aerosol are needed to elucidate pollution sources, gain insights into atmospheric chemistry, and evaluate changes in air quality. Fourier transform infrared absorption (FT-IR) spectrometry can be used to characterize atmospheric organic matter (OM) and its composition via functional groups of aerosol filter samples in air monitoring networks and research campaigns. We have built FT-IR spectrometry functional group calibration models that improve upon previous work, as demonstrated by the comparison of current model results with those of previous models and other OM analysis methods. Laboratory standards that simulated the breadth of the absorbing functional groups in atmospheric OM were made: particles of relevant chemicals were first generated, collected, and analyzed. Challenges of collecting atmospherically relevant particles and spectra were addressed by including interferences of particle water and other inorganic aerosol constituents and exploring the spectral effects of intermolecular interactions. Calibration models of functional groups were then constructed using partial least-squares (PLS) regression and the collected laboratory standard data. These models were used to quantify concentrations of five organic functional groups and OM in 8 years of ambient aerosol samples from the southeastern aerosol research and characterization (SEARCH) network. The results agreed with values estimated using other methods, including thermal optical reflectance (TOR) organic carbon (OC; R2=0.74) and OM calculated as a difference between total aerosol mass and inorganic species concentrations (R2=0.82). Comparisons with previous calibration models of the same type demonstrate that this new, more complete suite of chemicals has improved our ability to estimate oxygenated functional group and overall OM concentrations. Calculated characteristic and elemental ratios including OM∕OC, O∕C, and H∕C agree with those from previous work in the southeastern US, substantiating the aerosol composition described by FT-IR calibration. The median OM∕OC ratio over all sites and years was 2.1±0.2. Further results discussing temporal and spatial trends of functional group composition within the SEARCH network will be published in a forthcoming article.

Synthesis and characterization of a new ceramic nanomaterial SiO2/NPsSm2O3/C-graphite for the development of electrochemical sensors

A new ceramic nanomaterial, SiO2/NPsSm2O3/C-graphite (specific surface area 340 m2 g−1), obtained by the sol-gel process, was synthesized for industrial, pharmaceutical, and environmental purposes. Information on the ceramic formation dynamics and its behavior were obtained by determining the following parameters: surface area, pore volume, imaging and three-dimensional appearance (scanning electron microscopy, coupled to dispersive energy spectroscopy), molecular structure and the presence of functional groups (thermogravimetry, Fourier-transform infrared absorption spectroscopy, and 29Si nuclear magnetic resonance), and electrochemical behavior. SiO2/NPsSm2O3/C-graphite was used to construct electrodes with promising properties and showed that it can be used as a base substrate for the immobilization of electroactive species in electrochemistry and electrocatalysis.

Photothermally-driven thermo-oxidative degradation of low density polyethylene: heterogeneous heating plus a complex reaction leads to homogeneous chemistry

Photothermal heating from embedded nanoparticles, a process whereby visible light is converted into heat resulting in a high temperature in each particle’s immediate vicinity, was utilized to degrade low density polyethylene (LDPE) via thermo-oxidation. The spatially-varying steady-state photothermal temperature field is a potential mechanism by which ambient light (e.g. sunlight) could be used to drive chemical reactions within solid materials and may result in a non-uniform pattern of products, an advantage or disadvantage depending on application. Novel approaches to control polymer degradation are of interest because of the goal of remediating plastic waste, including autonomous means to minimize its effect when unconfined in the environment. For thermoplastic auto-oxidation, heterogeneous degradation would likely enhance deleterious micro-fragmentation however, the multi-step, multi-site nature of the reaction mitigated the temperature non-uniformity. A photothermally-heated LDPE nanocomposite with silver nanoparticle and cobalt-stearate additives showed degradation, characterized by ultraviolet–visible and Fourier-transform infrared absorption spectroscopy, electron microscopy, and mechanical testing, nearly identical to that resulting from uniform conventional treatment at the same average temperature.

Vibrational Fingerprint of Erlotinib: FTIR, RS, and DFT Studies

In this study, we provide the first Fourier-transform infrared absorption spectroscopy (FTIR) and Raman spectroscopy (RS) analysis of a vibrational fingerprint of erlotinib, a drug which is applied in non-small cell lung cancer therapy, in solid state and solution in different pH conditions. Additionally, the performed DFT theoretical calculations in vacuum and PCM models support the interpretation of vibrational spectra and give insight into an optimized spatial configuration of the investigated drug. The present considerations show vibrational structure of erlotinib and details of its molecular geometry. Furthermore, we discuss the pH condition where the protonated –NH+ and C=N+ forms occur and indicate the spectral changes characteristic for the erlotinib protonation. It is of great of importance to better understand biological activity of the drug and to develop new tyrosine kinase inhibitors.

Intra-dimer row and inter-dimer row coupling of the vibrational modes of chemisorbed CO on Si(001)-c(4×2) observed by angle-dependent transmission infrared spectroscopy.

The vibrational modes of chemisorbed CO on a Si(001) surface are investigated by means of transmission Fourier-transform infrared absorption spectroscopy. We observed the three components corresponding to the stretching vibration of the terminal-site CO adsorbed on the down-dimer sites of a Si(001) surface. The symmetric stretching vibration and asymmetric stretching vibration are observed separately. This assignment is consistent with the polarization dependence of the incident light and with the vibrational modes obtained by performing theoretical calculations. We found that both the intradimer row and interdimer row coupling should be considered to explain the appearance of the three components.