Quantitative and multicomponent analysis of prevalent urinary calculi using Raman spectroscopy

This study established a quantitative micro‐Raman spectroscopic (MRS) method for measuring multicomponents (binary and ternary compositions) of prevalent urine calculi extracted from the ureter after the ureteroscopic lithotripsy (URSL) procedure. The analysis used calibration curves of known mixtures of synthetically prepared calcium oxalate monohydrate (COM), hydroxyapatite (HAP), calcium oxalate dehydrate (COD), dicalcium phosphate dehydrate (DCPD), and uric acid. A variety of samples of binary and ternary mixtures including COM/HAP, COM/COD, COD/HAP, COM/uric acid, COD/uric acid, HAP/uric acid, HAP/DCPD, and COM/COD/HAP were prepared in various concentration ratios for use as the basis of the quantitative analysis. Intensities of the characteristic bands at 961 cm⁻¹ (I_HAP), 986 cm⁻¹ (I_DCPD), 1402 cm⁻¹ (I_UricAcid), 1462 cm⁻¹ (I_COM), and 1477 cm⁻¹ (I_COD) were used for the calculation. We derived a set of quantitative analysis equations for the ternary composition COD/COM/HAP group by combining two binary equations from the groups COM/COD and the HAP/COM. This study quantitatively measured 18 urine samples extracted from the 18 patients' ureters after the URSL procedure. Fifteen samples were binary mixtures, whereas three samples were ternary mixtures. This research successfully applied the quantitative MRS‐based analysis technique from bench to bedside. Copyright © 2012 John Wiley & Sons, Ltd.     

Infrared spectroscopy of solids

For materials like small gap semiconductors or intercalated layered compounds the general form of the complex dielectric function is: ϵ(ω) = ϵ_x + Δϵ_inter + Δϵ_intra + Δϵ_ph, where ϵ_∞is the high frequency dielectric constant due to all interband transitions except the uppermost valence band and the lowest conduction band, Δϵ_inter is the contribution to the dielectric constant due to this two bands in particular, Δϵ_intra is the contribution due to intraband free carrier transitions and Δϵ_ph is the contribution due to lattice vibrations. The contribution from transitions between valence and conduction bands to the imaginary part of the dielectric function Δϵ_inter(ω,T) for a narrow gap material can be readily calculated in the random phase approximation (RPA) formalism. The real part Δϵ_inter is obtained by performing the Kramers-Kronig inversion on the expression Δϵ_inter. Dielectric function of HgTe between 8 and 300 K is discussed. The interband contribution to the complex dielectric function in a layered intercalation compound is also examined. Pure graphite, first and second stage compounds are treated as an example. Reflectivity and magnetoreflectivity spectra simultaneously determining the plasma and the cyclotron frequencies, allow one to measure the free carrier density, hence the Fermi level, and the effective mass of the carriers. The variation of the effective mass as a function of the position of the Fermi level traces the energy bands dispersion relation. An example of such investigations is given for PbSe layered materials like Bi₂Se₃ are also studied by infrared reflectivity spectroscopy. Intercalation of such materials increases the free carrier population which consequently moves the Fermi level up in the conduction band. Analysis of reflectivity spectra allows an accurate determination of the free carrier concentration and gives a useful tool for the investigation of atom insertion in layered materials. Recent experiments on the intercalation of Li in a certain number of layered materials will be presented. In the frame of the classical theory of independent harmonic oscillators, the phonon contribution to the dielectric function is given by the sum of transverse modes for each oscillator with the corresponding damping parameters and oscillator strength. The complex dielectric function can then be written as a set of separate equations for the real and imaginary parts of the wave-number-dependent dielectric function. In the spectral region when phonon and plasmon frequencies may coincide a strong plasmon-phonon coupling will be experienced. In a simple model with one LO and one TO frequency, one expects two singularities at the two maxima of the function 1m −ϵ⁻¹; representing longitudinal modes. The frequencies generally labeled ω₊ and ω_- correspond to longitudinal oscillations with the lattice and electron plasma vibrating, respectively, in phase and 180° out of phase. In small gap materials the situation is more complex. Because of the particular band structure, the contribution Δϵ_inter(ω) must be included. In some cases it also becomes necessary to include additional oscillators with strong polar character corresponding to a particular defect or to additional vibrations. The implications of all these fundamental concepts in the investigation of high Tc materials is discussed and examples given.     

Infrared laser modulation spectroscopy

The lack of sensitivity in far infrared of conventional modulation techniques can be overcome by the use of a laser beam as a powerful high resolution infrared source. As an illustration of these features we describe a thermoreflectance experiment performed on mercury telluride using a frequency stabilised CO₂ laser. In this experiment a thin slab of HgTe was illuminated by the beam of the laser. A continuous shift of the Γ_6v?Γ_8c energy interval was produced by a slow temperature variation while the sample was submitted to a slight temperature modulation obtained by low frequency Joule heating. Synchronous and direct detection of the reflected beam gave the relative variation of reflectivity as a function of the sample temperature. Several spectra obtained at different emission lines enable us to determine the energy difference (E_g) between Γ_6v and Γ_8c inverted states. As a first approach a qualificative fit has been obtained with a simple model of dielectric constant and its temperature derivative. These results give the first direct determination of E_g near room temperature E_g = ? 117.04 meV at T = 286 ± 2 K.     

Infrared diode laser spectroscopy

Three types of lasers (double-heterostructure 66 K InAsSb/InAsSbP laser diode, room temperature, multi quantum wells with distributed feedback (MQW with DFB) (GaInAsSb/AlGaAsSb based) diode laser and vertical cavity surface emitting lasers (VCSELs) (GaSb based) have been characterized using Fourier transform emission spectroscopy and compared. The photoacoustic technique was employed to determine the detection limit of formaldehyde (less than 1 ppmV) for the strongest absorption line of the v₃ + v₅ band in the emission region of the GaInAsSb/AlGaAsSb diode laser. The detection limit (less than 10 ppbV) of formaldehyde was achieved in the 2820 cm⁻¹ spectral range in case of InAsSb/InAsSbP laser (fundamental bands of v₁, v₅). Laser sensitive detection (laser absorption together with high resolution Fourier transform infrared technique including direct laser linewidth measurement, infrared photoacoustic detection of neutral molecules (methane, form-aldehyde) is discussed.     

Infrared spectroscopy of nano-porous silicon

The first measurements of dielectric-permittivity and conductivity spectra of several samples of nano-porous silicon prepared by anodization of low-resistance monocrystalline silicon are performed at room temperature by means of subterahertz and IR spectroscopy in the frequency range 7–4000 cm^?1. The obtained spectra are analyzed in terms of the effective-medium theory with a size-dependent dielectric-response function of nanoinclusions and average dielectric parameters of the surronding medium. It is found that the dielectric properties of the inclusions are dependent on nano-size effects such as charge-carrier scattering at the boundaries of the nanocrystallites and increase in the band-gap energy due to the quantum size effect. The geometric and dielectric characteristics of silicon nano-size inclusions are determined. We consider the mechanisms of variation in the wide-band dielectric permittivity and conductivity spectra of monocrystalline silicon during transformation of its structure from monocrystalline to nano-porous.     

Infrared spectroscopy of ICAO taggants

The IR absorption spectra of the ICAO taggants, ethylene glycol dinitrate (EGDN), o-mononitrotoluene (2-NT), p-mononitrotoluene (4-NT) and 2,3-dimethyl-2,3-dinitrobutane (DMDNB) in the vapor phase, are studied at room temperature over a wide frequency range (500–4000 cm^–1). The pre-assignment of the observed vibrational bands was performed. Modern quantum-chemical methods are applied to calculate the equilibrium geometries of these molecules and the frequencies of their fundamental vibrations. For the most intense bands of 2-NT and 4-NT, the absorption cross sections are estimated. Based on analysis of current laser technology, it has been concluded that their use in conjunction with the available spectroscopic data makes it possible to reliably perform local and remote detection and identification of ICAO taggants in an open atmosphere in real time.     

Infrared diode laser spectroscopy of the BrO radical

The fundamental vibration-rotation band of the ⁷⁹BrO and ⁸¹BrO radicals in the ${}^2\text{Π}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ ground electronic state was observed in the region 700–760 cm^?1 by using a Zeeman-modulated infrared diode laser spectrometer. The BrO radical was generated directly in a multiple reflection Zeeman cell by a 60-Hz discharge in a mixture of Br₂ and O₂. The observed absorption lines, 20 and 22 in number for ⁷⁹BrO and ⁸¹BrO, rspectively, were combined with the microwave data of Cohen et al. [J. Mol. Spectrosc.87, 459–470 (1981)] and were subjected to least-squares analysis to determine the rotational and centrifugal distortion constants for both the v = 0 and v = 1 states and also the band origin. The band origin obtained for ⁸¹BrO, 721.92814(57) cm^?1, gives a support to the value 714 (10) cm^?1 estimated by Cohen et al. using the microwave data and also the result 722.1 ± 1.1 cm^?1 obtained by Barnett et al. [Canad. J. Phys.59, 1908–1916 (1981)] from a reanalysis of the A²Π_i-X²Π_i absorption spectrum.     

Infrared diode laser spectroscopy of the PO radical

Vibration-rotation transitions of the PO radical in the X²Π_r state have been observed by a tunable infrared diode laser spectrometer. The analysis of the observed spectra gave the molecular constants in the v = 1 state and the band origin to be B = 0.7250107(36), D = 1.0253(60) × 10^?4, A_J = 0.997(24) × 10^?4, p = 0.006323(33), A₁ - A₀ = 0.16354(78), and ν₀ = 1220.24901(43), all in cm^?1 units with three standard errors in parentheses, where the v = 0 parameters were fixed to the values previously reported. The equilibrium internuclear distance was determined to be $\text{r}{}_{\mathrm{<mtext>e</mtext>}}\text{= 1.476370(15)}\text{A}\text{?}$.     

Infrared spectroscopy of the intermediate-valence semiconductor YbB12

The dynamic conductivity and permittivity spectra of the intermediate-valence compound YbB₁₂ are measured in the frequency range (6–10⁴) cm^?1 (quantum energy 0.75 meV-1.24 eV) at temperatures of 5–300 K. Analysis of the spectral singularities associated with the response of free charge carriers has made it possible for the first time to determine the temperature dependences of their microscopic parameters, viz., concentration, effective mass, relaxation frequency and time, mobility, and plasma frequency. It is shown that the relaxation frequency decreases upon cooling from 300 K to the coherence temperature T ^* = 70 K for YbB₁₂, which is mainly associated with the phonon mechanism of scattering of charge carriers. For cooling below the coherence temperature T ^* = 70 K, the temperature dependence of the relaxation frequency for charge carriers of the Fermi-liquid type is found to be γ ～ γ₀ + T ², while their effective mass and relaxation time increase, respectively, to m ^*(20 K) = 34m ₀ (m ₀ is the free electron mass) and τ(20 K) = 4 × 10^?13 s, indicating the establishment of coherent scattering of carriers from localized magnetic moments of the f centers. At a temperature of T = 5 K, the conductivity spectrum contains an absorption line at a frequency of 22 cm^?1 (2.7 meV); the origin of this line can be associated with the exciton-polaron bound state. Since such a state was observed earlier in other intermediate-valence semiconductors (such as SmB₆, TmSe_1?x Te, and (Sm, Y)S), it is probably typical of this class of compounds.     

Infrared diode laser spectroscopy of the NS radical

The v = 1 ← 0 vibration-rotation bands of the NS radical in the $\text{X}{}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and $\text{X}{}^2\text{Π}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ electronic states were observed by using a tunable diode laser. From the least-squares analysis the band origins were determined to be 1204.2755(12) and 1204.0892(19) cm^?1, respectively, for $\text{X}{}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and $\text{X}{}^2\text{Π}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$. The rotational and centrifugal distortion constants and the internuclear distance in the X²Π electronic state were obtained as follows: B_e = 0.775549(10) cm^?1, D_e = 0.00000129(33) cm^?1, and $\text{r}{}_{\mathrm{e}}\text{= 1.49403(4)}\text{A}\text{?}$, with three standard deviations indicated in parentheses.     

Infrared spectroscopy with synchrotron radiation

Up to now, storage rings have been used as sources of radiation on the X-ray and the u.v. part of the spectrum. It is shown that, with a specially designed part, a storage ring like ACO at Orsay is a very powerful far-infrared source, whose advantages over classical wide band sources are reviewed.     

Infrared diode laser spectroscopy of the CF radical

The fundamental bands of the CF radical in the $\text{X}{}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and $\text{X}{}^2\text{Π}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ electronic states were observed by using an infrared tunable diode laser as a source. Zeeman modulation could be used in detecting lines not only in the ${}^2\text{Π}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ state, but also in ${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, because the CF radical deviates considerably from Hund's case (a). From the least-squares analysis of the observed spectra, the following molecular constants were obtained: B_e = 1.416 704 (37) cm^?1, α_e = 0.018 419 (50) cm^?1, $\text{r}{}_{\mathrm{e}}\text{= 1.271 977 (17)}\text{A}\text{?}$, D_e = 6.68 (15) × 10^?6cm^?1, p₀ = 0.008 580 (21) cm^?1, p₁ = 0.008 52 (11) cm^?1, and $\text{ν}{}_0\text{= 1286.1281 (5)}\text{cm}{}^{\mathrm{?1}}$, with three standard errors in parentheses.     

Infrared reflectivity spectroscopy of electron-phonon interactions

The crucial role of electron-phonon interactions and their signatures in optical conductivity deduced from the analysis of infrared-visible reflection spectra is reviewed. The usefulness of a general phenomenological model able to describe the couplings of phonons, polarons, plasmon, superconducting condensate, is discussed. Among other examples of applications, the problem of the signature of Cooper pair condensation in the superconducting phase of high-T _c cuprates is discussed in the framework of London and Mattis-Bardeen models.     

Infrared laser stark spectroscopy of ammonia

Refined values for molecular constants of¹⁴NH₃ and less precise values for those of¹⁵NH₃ and¹⁴NH₂D were obtained with laser Stark spectroscopy. Paper was prepared for presentation at FICOLS     

Infrared Fourier transform spectroscopy of PH

The infrared vibration-rotation spectrum of the PH radical was observed in emission using a high-resolution Fourier transform spectrometer. The observation of five bands (1-0, 2-1, 3-2, 4-3, and 5-4) allowed the first six vibrational energy levels of the ground X³Σ⁻ state to be characterized. An RKR potential curve for the ground state was computed.     

Infrared spectroscopy of Landau levels of graphene

We report infrared studies of the Landau level (LL) transitions in single layer graphene. Our specimens are density tunable and show in situ half-integer quantum Hall plateaus. Infrared transmission is measured in magnetic fields up to B=18 T at selected LL fillings. Resonances between hole LLs and electron LLs, as well as resonances between hole and electron LLs, are resolved. Their transition energies are proportional to sqrt[B], and the deduced band velocity is (-)c approximately equal to 1.1 x 10(6) m/s. The lack of precise scaling between different LL transitions indicates considerable contributions of many-particle effects to the infrared transition energies.     

Infrared spectroscopy on lead silicate glass

The reflectance spectra of some lead silicate glasses of general formula (PbO)_x(SiO₂)_y have been measured in the infrared frequency range from 50 to 4000 cm^–1. The dispersion and absorption spectra in the range 50–2000 cm^–1 have been calculated from the reflectance data using the Kramers-Kronig relations. The band at 135 cm^–1 is assigned to the stretching vibration of lead-oxygen bonds. The shoulder band of the silicon-oxygen stretching mode at 900 cm^–1 shows a weak coupling of those bonds to the Pb²⁺ modifier. The vibration strength of those bands shows that the number of the Pb²⁺ modifier increases first up approximately to 50 Mol% with the increase of PbO content and then decreases rapidly. It indicates that different PbO content causes different structural forms in lead silicate glasses: The addition of small amounts of PbO to vitreous silica serves to modify the continuous three-dimensional silica network: whereas in those glasses with a high lead content, the influence of the cation, Pb²⁺, appears to lie between that of network former and network modifier. This result is in agreement with the structural model of Worrel and Henshall.