The asilomar conference on ion spectroscopy,October 16–20, 2009

The ASMS conference on ion spectroscopy brought together at Asilomar on October 16–20, 2009 a large group of mass spectrometrists working in the area of ion spectroscopy. In this introduction to the field, we provide a brief history, its current state, and where it is going. Ion spectroscopy of intermediate size molecules began with photoelectron spectroscopy in the 1960s, while electronic spectroscopy of ions using the photodissociation “action spectroscopic” mode became active in the next decade. These approaches remained for many years the main source of information about ionization energies, electronic states, and electronic transitions of ions. In recent years, high-resolution laser techniques coupled with pulsed field ionization and sample cooling in molecular beams have provided high precision ionization energies and vibrational frequencies of small to intermediate sized molecules, including a number of radicals. More recently, optical parametric oscillator (OPO) IR lasers and free electron lasers have been developed and employed to record the IR spectra of molecular ions in either molecular beams or ion traps. These results, in combination with theoretical ab initio molecular orbital (MO) methods, are providing unprecedented structural and energetic information about gas-phase ions.     

ω1,-Scaling pulse sequences for two-dimensional homonuclear multiple-quantum spectroscopy

New pulse schemes have been proposed for different possibilities of ω₁-scaling in two-dimensional homonuclear multiple-quantum spectroscopy. The advantages of the methods for resolution enhancement and sensitivity enhancement have been demonstrated.     

Spectroscopic techniques to characterize the spin state: Vibrational,optical, Mössbauer,NMR, and X-ray spectroscopy

Basic principles and recent work using probes including Mössbauer, optical, X-ray, and vibrational spectroscopies to follow the transitions in spin crossover complexes are reviewed. X-ray spectroscopy, being a relatively lesser-known probe, is discussed in more detail. X-ray spectroscopic methods have been used in the spin crossover field mostly to elucidate surface phenomena, ultrafast dynamics, and high pressure effects, but recent technical developments provide perspectives for a more widespread use of these powerful techniques in home laboratories.     

A simple,rapid, and robust “on-the-go” identity testing of biotherapeutics using FTIR spectroscopy

The stunning rise of biotherapeutics as successful treatments of complex and hard-to-treat diseases, in particular cancer, has necessitated the development of a rapid analytical method capable of differentiating these otherwise significantly similar antibody-based products. The existing methods for product identification pose significant drawbacks in terms of the consumption of time and labor. Here, we present an FTIR spectroscopy-based simple, rapid, and robust method that is capable of differentiating between the biotherapeutics (both innovator products and biosimilars). The proposed approach uses partial least-squares-discriminant analysis to pinpoint subtle differences in the FTIR spectra of the samples, enabling us to not only identify the product but also calculate its concentration. This FTIR-based method can be used to fulfill the identity testing requirement of a pharmaceutical drug in its final packaged form set by the US Food and Drug Administration. Along with this, identity testing can also be deployed at multiple steps in the manufacturing process and can also be used by the appropriate regulatory or government agency for tackling counterfeits of biotherapeutic products.     

High-Tc superconductors studied by57Co,57Fe,119Sn,and151Eu mössbauer spectroscopy

¹⁵¹Eu,¹¹⁹Sn,⁵⁷Fe, and⁵⁷Co Mössbauer spectroscopy was used to study YBa₂Cu₃O_7– high-T_c superconductors in which sites were replaced by various Mössbauer nuclides in order to get information about site preference and structural changes. By decomposition of the Mössbauer spectra, the Y site substituted by Eu and the Cu sites occupied by Sn, Fe, and Co substituents were identified. It was found that Fe and Co prefer the Cu(1) site while Sn prefers the Cu(2) site in the orthorhombic perovskite lattice of these superconductors. The site preference is enhanced in the presence of additional substituents. A sequence of thermal heat treatments permits reversible cycling of⁵⁷Co between the two copper sites in the YBa₂[Cu(⁵⁷Co)]₃O_7– perovskite. In all cases Eu(III) and Sn(IV) states are determined, but the valence state of Fe and Co can be both three and four. BelowT _c, low-temperature phase transformation and phonon softening were shown from the anomalous temperature dependence of isomer shifts and the area fractions of¹⁵¹Eu and¹¹⁹Sn Mössbauer spectra of EuBa₂(Cu_1-xSn_x)₃O_7- cuprates.     

Raman spectroscopy in the near infrared – a most capable method of vibrational spectroscopy

Raman spectroscopy has enjoyed a dramatic improvement during the last years: The interference by the fluorescence of impurities is virtually eliminated, the sample preparation is considerably easier as for infrared spectroscopy and many applications in routine analytics, quality control and process control in various branches of industry are now possible. It is shown that the up-to-date near-infrared Raman spectrometers now meet most demands for a modern analytical instrument concerning applicability, analytical information and convenience. It can be anticipated that Raman spectroscopy will catch up infrared spectroscopy, the current workhorse of vibrational spectroscopy.     

Vibrational overtone spectroscopy, energy levels, and intensities of (CH3)3C-C≡C-H

The vibrational overtone spectra of the acetylenic (Δυ = 4, 5) and methyl (Δυ = 5, 6) C-H stretch transitions of tert-butyl acetylene [(CH(3))(3)C-C≡C-H] were obtained using the phase shift cavity ring down (PS-CRD) technique at 295 K. The C-H stretch fundamental and overtone absorptions of the acetylenic (Δυ = 2 and 3) and methyl (Δυ = 2-4) C-H bonds have been obtained using a Fourier transform infrared and near-infrared spectrophotometer. Harmonic frequency ω(ν(1)) and anharmonicities x(ν(1)) and x(ν(1), ν(24)) are reported for the acetylenic C-H bond. Molecular orbital calculations of geometry and vibrational frequencies were performed. A harmonically coupled anharmonic oscillator (HCAO) model was used to determine the overtone energy levels and assign the absorption bands to vibrational transitions of methyl C-H bonds. Band strength values were obtained experimentally and compared with intensities calculated in terms of the HCAO model where only the C-H modes are considered. No adjustable parameters were used to get order of magnitude agreement with experimental intensities for all pure local mode C-H transitions.     

Synthesis,X-ray crystallography characterization,vibrational spectroscopy,and DFT theoretical studies of a new organic–inorganic hybrid material

A new hybrid material based on polyoxomolybdate, [C₂H₆N₂O–H]₃[(PO₄)Mo₁₂O₃₆] · 3H₂O (1), has been synthesized and characterized by elemental analysis, infrared and mass spectroscopy, proton nuclear magnetic resonance and single-crystal X-ray diffraction. Compound 1 crystallizes in the hexagonal system, space group R-3, a = 19.0833(6) Å, c = 20.8672(13) Å, V = 581.1(5) ų, Z = 6, R1 = 0.0202, wR2 = 0.0508. The methyluronium moiety and 12-molybdophosphate anion are held together in a network through hydrogen-bonding and electrostatic interactions. Each methylurea molecule, which is protonated, is stabilized via present strong hydrogen bonding with water molecules in the unit cell. Since this strong hydrogen bonding can play an important role in the formation of unique novelty of titled supramolecular network, we have carried out theoretical calculations on geometrical parameters, stabilization energies, and atomic charges based on natural bond orbital (NBO) analyses and then have compared with those of the neutral methylurea molecule. Our calculations have been done with the B3LYP method of density functional theory (DFT).     

Terahertz time-domain spectroscopy of some pentoses

1 Introduction Terahertz time-domain spectroscopy (THz-TDS) is a new spectral technique based on femto-second laser technology developed since the 1980s[1]. Terahertz (THz) waves lie between the infrared and microwave bands in the electromagnetic spectrum covering the frequency range from 100 GHz to 10 THz. Despite great scientific interest, the THz frequency range re- mains one of the least tapped regions of the electro- magnetic spectrum because there are neither conven- ient high-power…     

Identification of γ-ray irradiated medicinal herbs using pulsed photostimulated luminescence, thermoluminescence, and electron spin resonance spectroscopy

Dried herbal samples consisting of root, rhizome, cortex, fruit, peel, flower, spike, ramulus, folium, and whole plant of 20 different medicinal herbs were investigated using pulsed photostimulated luminescence (PPSL), thermoluminescence (TL), and electron spin resonance spectroscopy (ESR) to identify γ-ray irradiation treatment. Samples were irradiated at 0–50 kGy using a 60Co irradiator. PPSL measurement was applied as a rapid screening method. Control samples of 19 different herbs had photon counts less than the lower threshold value (700 counts 60 s−1). The photon counts of non-irradiated clematidis radix and irradiated evodia and gardenia fruits were between the lower and upper threshold values (700–5,000 counts 60 s−1). TL ratios, i.e., integrated areas of the first glow (TL1)/the second glow (TL2), were found to be less than 0.1 in all non-irradiated samples and higher than 0.1 in irradiated ones providing definite proof of radiation treatment. ESR spectroscopy was applied as an alternative rapid method. In most of the irradiated samples, mainly radiation-induced cellulosic, sugar, and relatively complicated carbohydrate radical ESR signals were detected. No radiation-specific ESR signal, except one intense singlet, was observed for irradiated scrophularia and scutellaria root and artemisiae argyi folium. Figure PPSL can be used as a rapid simple preliminary screening method and a combination of ESR and TL tests for a definite proof of gamma irradiation treatment of medicinal herbs.     

Synthesis,structure, and spectroscopy of two benzil-based α-diimine ligands and their palladium(II) complexes

Two α-diimine ligands were prepared in 60–70% yield via p-toluenesulfonic acid-catalyzed condensation reactions from benzil with 4-bromoaniline and with p-anisidine. Palladium(II) complexes were prepared from both ligands in 70–80% yield. X-ray structures were obtained for the ligand prepared from p-anisidine and its palladium(II) complex. A notable feature observed in the former was its unconjugated C–N double bonds, both in the (E)-configuration. The latter structure possessed two molecules of the metal complex in its unit cell, both of which have diimine cores with a degree of conjugation and a nonideal square-planar geometry around palladium caused by the small bite angles (79.61(3) and 79.15(3)°) of the diimine ligands. Solution-phase electronic absorption spectra of the ligands in chloroform have two bands from π→π ^? and n→π ^? transitions at 269–345?nm. Absorption spectra of the complexes in chloroform exhibited bands attributed to ligand-centered transitions that were red-shifted as compared to free ligands. Only the spectrum obtained from a chloroform solution of the palladium(II) complex with the diimine ligand prepared from p-anisidine featured a band at approximately 520?nm, which was assigned to a combination of d _π(Pd)→π ^? and n(Cl)→π ^? transitions.     

Low pressure plasma spectroscopy – Spectrochemical analysis,technology process investigation and fundamental spectroscopic data

Low pressure plasma, its characteristics, excitation sources and applications are shortly presented. The paper is focused on three areas of low pressure plasma spectroscopy, i.e. spectrochemical analysis, investigation of technology processes and fundamental reference data. Matrix effects occurring in spectrochemical analyses by means of hollow cathode discharges are presented. Investigation and monitoring of processes of production of new materials in glow discharges are shown. Applicability of low pressure plasma for the determination of atomic (transition probabilities) and molecular reference data (electronic, vibrational and rotational constants) and utilization of molecular data are discussed.     

Unsymmetrical 1λ3-1,2,4,6-thiatriazinyls with aryl and trifluoromethyl substituents: synthesis, crystal structures, EPR spectroscopy, and voltammetry

A general synthetic route to 3-trifluoromethyl-5-aryl-1λ(3)-1,2,4,6-thiatriazinyl radicals was developed. X-ray structures were obtained for all five neutral radicals and show that they exist in the solid state as cofacial dimers linked by S···S contacts. X-ray structures were also obtained for two of the precursor chlorothiatriazines along with several aryl N-imidoylamidines, p-methoxybenzamidine, and N-chlorosulfonyl-N,N'-benzamidine. Cyclic voltammetric studies were performed on the [R(2)C(2)N(3)S](?) radicals in CH(3)CN and CH(2)Cl(2) with [(n)Bu(4)N][PF(6)] as the supporting electrolyte under vacuum conditions in an all-glass electrochemical cell. The results provide quasi-reversible formal potentials for the [R(2)C(2)N(3)S](-/0) process in the range of -0.61 to -0.47 V, irreversible peak potentials for the [R(2)C(2)N(3)S](0/+) process from 0.59 to 0.91 V at lower concentrations, and the appearance of a second, reversible oxidation process from 0.69 to 0.94 V at higher concentrations (versus the Fc(0/+) couple; Fc = ferrocene). This behavior was indicative of monomer-dimer equilibrium in solution, as ascertained from digital models of the voltammograms. There is a small but measurable trend in both the oxidation and reduction potentials with varying remote aryl substituents. EPR spectra were obtained for all five neutral radicals in CH(2)Cl(2) solutions, which confirm the concentration of the unpaired electron density on the heterocyclic core. Trends were also seen in the hyperfine splitting constants a(N) with varying remote aryl substituents. Calculations were performed for all three oxidation states of the [R(2)C(2)N(3)S](-/?/+) monomeric rings; the resulting theoretical redox energies correlate well with solution phase voltammetric data.     

Vibrational spectroscopy: a 'vanishing' discipline?

The aim of this tutorial review is to convince a broad readership that vibrational spectroscopy, although according to some vibrational spectroscopists seemingly less in focus nowadays than in days past, is far from 'dead'. It may seem to some that infrared and Raman spectroscopy are less in focus than in times past, despite the unique analytical capabilities. Vibrational spectroscopy is particularly powerful for non-destructive characterisation of substances, including living material. But compared to the past, a shift in applications has taken place, bringing new opportunities. This is partly due to the introduction of new features, including imaging and 2D correlation spectroscopy. Another factor is the recognition that vibrational spectroscopy can play a role in new rather than only in the traditional fields of application, e.g. new applications in the life-science field (living cells, cancer research), the characterisation of soil. But also the traditional application in catalysis sees new development within the context of Operando spectroscopy.     

Negative ion photoelectron spectroscopy of teo−

We have recorded the photoelectron spectrum of Te0⁻ using a hot-cathode discharge ion source and a negative ion photoelectron spectrometer. The adiabatic electron affinity of TeO is determined to be 1.697±0.022 eV. The negative ion parameters determined in this work are: (w_e″(TeO⁻) = 690 ± 80 cm⁻¹, r_e″(TeO⁻) = 1.884 ± 0.028 Å. and D_o