Raman spectroscopy of a sulfur dioxide visual sensor: The origin of the two colors in the solid sample

The vibrational spectroscopic characterization of a sulfur dioxide visual sensor was carried out using a Raman microscope system. It was observed the formation of two distinct complexes, that were characterized by the position and relative intensities of the bands assigned to the symmetric stretching, ν_s(SO₂), of the linked SO₂ molecules. In fact, in the yellowish orange complex, that corresponds to the 1:1 stoichiometry, only one band is observed, assigned to ν_s(SO₂) at ca. 1080 cm^?1 and, in the deep red complex, that corresponds to the 1:2 complex, at ca. 1070 and 1090 cm^?1 are observed. The variation of the relative intensities of the bands assigned to ν_s(SO₂) present in the Ni(II)·SO₂ complex, in different points of the sample, shows clearly the requirement of the Raman microscope in the vibrational characterization of this kind of molecular sensor.     

A Raman spectroscopic study of the antimonite mineral peretaite Ca(SbO)4(OH)2(SO4)2·2H2O

Raman spectra of mineral peretaite Ca(SbO)₄(OH)₂(SO₄)₂·2H₂O were studied, and related to the structure of the mineral. Raman bands observed at 978 and 980 cm^?1 and a series of overlapping bands observed at 1060, 1092, 1115, 1142 and 1152 cm^?1 are assigned to the SO₄^2? ν₁ symmetric and ν₃ antisymmetric stretching modes. Raman bands at 589 and 595 cm^?1 are attributed to the SbO symmetric stretching vibrations. The low intensity Raman bands at 650 and 710 cm^?1 may be attributed to SbO antisymmetric stretching modes. Raman bands at 610 cm^?1 and at 417, 434 and 482 cm^?1 are assigned to the SO₄^2? ν₄ and ν₂ bending modes, respectively. Raman bands at 337 and 373 cm^?1 are assigned to O–Sb–O bending modes. Multiple Raman bands for both SO₄^2? and SbO stretching vibrations support the concept of the non-equivalence of these units in the peretaite structure.     

Apparent molar heat capacities and apparent molar volumes ofY2(SO4)3(aq),La2(SO4)3(aq),Pr2(SO4)3(aq),Nd2(SO4)3(aq),Eu2(SO4)3(aq),Dy2(SO4)3(aq),Ho2(SO4)3(aq), andLu2(SO4)3(aq)atT = 298.15 K andp = 0.1 MPa

The apparent molar heat capacities C_{p, φ} ^∘ and apparent molar volumes V_φ ^∘ of Y₂(SO₄)₃(aq), La₂(SO₄)₃(aq), Pr₂(SO₄)₃(aq), Nd₂(SO₄)₃(aq), Eu₂(SO₄)₃(aq), Dy₂(SO₄)₃(aq), Ho₂(SO₄)₃(aq), and Lu₂(SO₄)₃(aq) were measured at T =  298.15 K and p =  0.1 MPa with a Sodev (Picker) flow microcalorimeter and a Sodev vibrating-tube densimeter, respectively. These measurements extend from lower molalities of m =  (0.005 to 0.018) mol ·kg ^− 1to m =  (0.025 to 0.434) mol ·kg ^− 1, where the upper molality limits are slightly below those of the saturated solutions. There are no previously published apparent molar heat capacities for these systems, and only limited apparent molar volume information. Considerable amounts of the R SO₄ ⁺ (aq) and R(SO₄)₂ ⁻ (aq) complexes are present, where R denotes a rare-earth, which complicates the interpretation of these thermodynamic quantities. Values of the ionic molar heat capacities and ionic molar volumes of these complexes at infinite dilution are derived from the experimental information, but the calculations are necessarily quite approximate because of the need to estimate ionic activity coefficients and other thermodynamic quantities. Nevertheless, the derived standard ionic molar properties for the various R SO₄ ⁺ (aq) and R(SO₄)₂ ⁻ (aq) complexes are probably realistic approximations to the actual values. Comparisons indicate that V_φ ^∘ {RSO₄ ⁺ , aq, 298.15K}  =  − (6  ±  4)cm³· mol ^− 1and V_φ ^∘ {R(SO₄)₂ ⁻ , aq, 298.15K}  =  (35  ±  3)cm³· mol ^− 1, with no significant variation with rare-earth. In contrast, values of C_{p, φ} ^∘ { RSO₄ ⁺ , aq, 298.15K } generally increase with the atomic number of the rare-earth, whereas C_{p, φ} ^∘ { R(SO₄)₂ ⁻ , aq, 298.15K } shows a less regular trend, although its values are always positive and tend to be larger for the heavier than for the light rare earths.     

A calorimetric and thermodynamic investigation of A2[(UO2)2(MoO4)O2] compounds with A = K and Rb and calculated phase relations in the system (K2MoO4 + UO3 + H2O)

A calorimetric and thermodynamic investigation of two alkali-metal uranyl molybdates with general composition A₂[(UO₂)₂(MoO₄)O₂], where A = K and Rb, was performed. Both phases were synthesized by solid-state sintering of a mixture of potassium or rubidium nitrate, molybdenum (VI) oxide and gamma-uranium (VI) oxide at high temperatures. The synthetic products were characterised by X-ray powder diffraction and X-ray fluorescence methods. The enthalpy of formation of K₂[(UO₂)₂(MoO₄)O₂] was determined using HF-solution calorimetry giving Δ_fH° (T = 298 K, K₂[(UO₂)₂(MoO₄)O₂], cr) = −(4018 ± 8) kJ · mol⁻¹. The low-temperature heat capacity, С_р°, was measured using adiabatic calorimetry from T = (7 to 335) K for K₂[(UO₂)₂(MoO₄)O₂] and from T = (7 to 326) K for Rb₂[(UO₂)₂(MoO₄)O₂]. Using these С_р° values, the third law entropy at T = 298.15 K, S°, is calculated as (374 ± 1) J · K⁻¹ · mol⁻¹ for K₂[(UO₂)₂(MoO₄)O₂] and (390 ± 1) J · K⁻¹ · mol⁻¹ for Rb₂[(UO₂)₂(MoO₄)O₂]. These new experimental results, together with literature data, are used to calculate the Gibbs energy of formation, Δ_fG°, for both phases giving: Δ_fG° (T = 298 K, K₂[(UO₂)₂(MoO₄)O₂], cr) = (−3747 ± 8) kJ · mol⁻¹ and Δ_fG° (T = 298 K, Rb₂[(UO₂)₂(MoO₄)], cr) = −3736 ± 5 kJ · mol⁻¹. Smoothed С_р°(Т) values between 0 K and 320 K are presented, along with values for S° and the functions [H°(T) − H°(0)] and [G°(T) − H°(0)], for both phases. The stability behaviour of various solid phases and solution complexes in the (K₂MoO₄ + UO₃ + H₂O) system with and without CO₂ at T = 298 K was investigated by thermodynamic model calculations using the Gibbs energy minimisation approach.     

Vibrational spectroscopic study of syngenite formed during the treatment of liquid manure with sulphuric acid

Syngenite (K₂Ca(SO₄)₂·H₂O), formed during treatment of manure with sulphuric acid, was studied by infrared, near-infrared (NIR) and Raman spectroscopy. C_s site symmetry was determined for the two sulphate groups in syngenite (P2₁/m), so all bands are both infrared and Raman active. The split ν₁ (two Raman+two infrared bands) was observed at 981 and 1000 cm⁻¹. The split ν₂ (four Raman+four infrared bands) was observed in the Raman spectrum at 424, 441, 471 and 491 cm⁻¹. In the infrared spectrum, only one band was observed at 439 cm⁻¹. From the split ν₃ (six Raman+six infrared) bands three 298 K Raman bands were observed at 1117, 1138 and 1166 cm⁻¹. Cooling to 77 K resulted in four bands at 1119, 1136, 1144 and 1167 cm⁻¹. In the infrared spectrum, five bands were observed at 1110, 1125, 1136, 1148 and 1193 cm⁻¹. From the split ν₄ (six infrared+six Raman bands) four bands were observed in the infrared spectrum at 604, 617, 644 and 657 cm⁻¹. The 298 K Raman spectrum showed one band at 641 cm⁻¹, while at 77 K four bands were observed at 607, 621, 634 and 643 cm⁻¹. Crystal water is observed in the infrared spectrum by the OH-liberation mode at 754 cm⁻¹, OH-bending mode at 1631 cm⁻¹, OH-stretching modes at 3248 (symmetric) and 3377 cm⁻¹ (antisymmetric) and a combination band at 3510 cm⁻¹ of the H-bonded OH-mode plus the OH-stretching mode. The near-infrared spectrum gave information about the crystal water resulting in overtone and combination bands of OH-liberation, OH-bending and OH-stretching modes.     

Hot band spectroscopy of CCO in the C–O stretching region: The (ν1 + 2ν3) − 2ν3 and (2ν1 + ν3) − (ν1 + ν3) bands

Two C–O stretching hot bands, (ν₁ + 2ν₃) − 2ν₃ and (2ν₁ + ν₃) − (ν₁ + ν₃), of the CCO radical in the ground electronic state were measured. These hot bands are red shifted by approximately 70 cm⁻¹ compared to the C–O stretching fundamental. CCO was produced in a discharge through a flowing mixture of carbon suboxide and helium. The spectra were recorded using a diode laser spectrometer. The band origins were determined to be 1904.32512(62) and 1902.69130(56) cm⁻¹ for (ν₁ + 2ν₃) − 2ν₃ and (2ν₁ + ν₃) − (ν₁ + ν₃), respectively. The measurements in this band together with previously reported frequencies in the C–C and C–O stretching regions were analysed to determine harmonic frequencies and anharmonicity constants.     

{Mo2O2S2}2+-directed synthesis of a polyoxotungstoarsenate(III). Structure and 183W NMR studies of the [(α–AsW9O33)3(WO(OH2))3(Mo2O2S2(H2O)4)]13− anion

Reaction of the [Mo₂O₂S₂(OH₂)₆]²⁺ aqua cation and [WO₄]^2? with the trivacant ion [α-B-AsW₉O₃₃]^9? in acidic condition (pH = 1.4) leads to the formation of a {Mo₂S₂O₂}-supported polyoxotungstate. The mixed salt NMe₄K₁₂[(α–AsW₉O₃₃)₃(WO(OH₂))₃(Mo₂O₂S₂(H₂O)₄)]?20H₂O (noted TMAK₁₂–1) has been obtained as single crystals and structurally characterized by X-ray diffraction analysis. The structural analysis of TMAK₁₂-1 reveals a molecular polyoxotungsto-arsenate (III) framework consisting of three α-{AsW₉O₃₃} subunits mutually linked by three {O = W-OH₂}⁴⁺ groups. The resulting triangular arrangement delimits a large “open-space”, lined on the periphery by six terminal oxygen atoms. The central cavity is partially filled by a single {Mo₂O₂S₂(OH₂)₄}²⁺ which spans two {AsW₉O₃₃} subunits. Furthermore, three potassium ions have been located, one being embedded within the central cavity and the other two, symmetrically distributed at the periphery of the central cavity. In the solid state, two anions 1 interact through hydrogen bonds and ionic contacts to give a large dimeric arrangement bordered by two TMA⁺ cations. 1 has been characterized in solution (Li⁺ salt) by its ¹⁸³W NMR spectrum which contains 16 lines in agreement with the C_s idealized symmetry assumed for the isolated anion 1. Infrared data and elemental analysis are also supplied.     

Heat capacities,third-law entropies and thermodynamic functions of the geometrically frustrated antiferromagnetic spinels GeCo2O4 and GeNi2O4 from T=(0 to 400) K

The molar heat capacities of GeCo₂O₄ and GeNi₂O₄, two geometrically frustrated spinels, have been measured in the temperature range from T=(0.5 to 400) K. Anomalies associated with magnetic ordering occur in the heat capacities of both compounds. The transition in GeCo₂O₄ occurs at T=20.6 K while two peaks are found in the heat capacity of GeNi₂O₄, both within the narrow temperature range between 11.4<(T/K)<12.2. Thermodynamic functions have been generated from smoothed fits of the experimental results. At T=298.15 K the standard molar heat capacities are (143.44 ± 0.14) J · K⁻¹ · mol⁻¹ for GeCo₂O₄ and (130.76 ± 0.13) J · K⁻¹ · mol⁻¹ for GeNi₂O₄. The standard molar entropies at T=298.15 K for GeCo₂O₄ and GeNi₂O₄ are (149.20 ± 0.60) J · K⁻¹ · mol⁻¹ and (131.80 ± 0.53) J · K⁻¹ · mol⁻¹ respectively. Above 100 K, the heat capacity of the cobalt compound is significantly higher than that of the nickel compound. The excess heat capacity can be reasonably modeled by the assumption of a Schottky contribution arising from the thermal excitation of electronic states associated with the CO²⁺ ion in a cubic crystal field. The splittings obtained, 230 cm⁻¹ for the four-fold-degenerate first excited state and 610 cm⁻¹ for the six-fold degenerate second excited state, are significantly lower than those observed in pure CoO.     

Phase ratios in the K2O-V2O4-SO3 system at high sulfur trioxide concentrations

Phase ratios in the three-component oxide system K₂O-V₂O₄-SO₃ in the region of the sulfur trioxide concentrations corresponding to its concentrations in the active component of vanadium catalysts for SO₂ to SO₃ conversion have been studied using powder X-ray diffraction, IR spectroscopy, microscopy, and chemical analysis. Four individual compounds (K₂VO(SO₄)₂, K₂(VO)₂(SO₄)₃, K₂VO(SO₄)₂S₂O₇, and K₂(VO)₂(SO₄)₂S₂O₇) and K₂(VO)₂(SO₄)₂S₂O₇ and VOSO₄-base solid solutions of composition K₂(VO)_2+x (SO₄)_2+x S₂O₇ (0 ≤ x ≤ 1.5) were found in the system. K₂VO(SO₄)S₂O₇ and K₂(VO)₂(SO₄)₂S₂O₇ lose their sulfur trioxide when heated above 350°C under an inert atmosphere, and convert to K₂VO(SO₄)₂ and K₂(VO)₂(SO₄)₃, respectively. This implies that K₂VO(SO₄)₂S₂O₇ and K₂(VO)₂(SO₄)₂S₂O₇, as well as K₂(VO)_2+x (SO₄)_2+x S₂O₇ solid solution, cannot exist in the active component of real industrial catalysts.     

Thermodynamic properties of Na2Ti6O13 and Na2Ti3O7: electrochemical and calorimetric determination

Standard values of Gibbs free energy, entropy, and enthalpy of Na₂Ti₆O₁₃ and Na₂Ti₃O₇ were determined by evaluating emf-measurements of thermodynamically defined solid state electrochemical cells based on a Na–β″-alumina electrolyte. The central part of the anodic half cell consisted of Na₂CO₃, while two appropriate coexisting phases of the ternary system Na–Ti–O are used as cathodic materials. The cell was placed in an atmosphere containing CO₂ and O₂. By combining the results of emf-measurements in the temperature range of 573⩽T/K⩽1023 and of adiabatic calorimetric measurements of the heat capacities in the low-temperature region 15⩽T/K⩽300, the thermodynamic data were determined for a wide temperature range of 15⩽T/K⩽1100. The standard molar enthalpy of formation and standard molar entropy at T=298.15 K as determined by emf-measurements are Δ_fH_m⁰=(−6277.9±6.5) kJ · mol⁻¹ and S_m⁰=(404.6±5.3) J · mol⁻¹ · K⁻¹ for Na₂Ti₆O₁₃ and Δ_fH_m⁰=(−3459.2±3.8) kJ · mol⁻¹ and S_m⁰=(227.8±3.7) J · mol⁻¹ · K⁻¹ for Na₂Ti₃O₇. The standard molar entropy at T=298.15 K obtained from low-temperature calorimetry is S_m⁰=399.7 J · mol⁻¹ · K⁻¹ and S_m⁰=229.4 J · mol⁻¹ · K⁻¹ for Na₂Ti₆O₁₃ and Na₂Ti₃O₇, respectively. The phase widths with respect to Na₂O content were studied by using a Na₂O-titration technique.     

Minerals from Macedonia: XVII. Vibrational spectra of some common appearing amphiboles

The vibrational (infrared and Raman) spectroscopy is used in order to identify and characterize the following amphibole minerals with general formula W_0–1X₂Y₅Z₈O₂₂(OH)₂ (W = Na, K; X = Na, Ca; Y = Mg, Fe²⁺, Fe³⁺, Al; Z = Si, Al) originating from the localities in the Republic of Macedonia: glaucophane, Na₂(Mg,Fe²⁺)₃(Fe³⁺,Al)₂Si₈O₂₂(OH)₂; tremolite–actinolite, Ca₂(Mg,Fe²⁺)₅Si₈O₂₂(OH)₂; hornblende (Na,K)_0–1Ca₂(Mg,Fe²⁺,Fe³⁺,Al)₅(Si,Al)₈ O₂₂(OH)₂ and arfvedsonite, NaNa₂(Mg,Fe²⁺)₄(Fe³⁺,Al)Si₈O₂₂(OH)₂. The chemical composition of these minerals is not necessarily fixed. It is due to the possibility to form solid solution series with other minerals being their end-members (for example, tremolite–ferro-actinolite series, Ca₂Mg₅Si₈O₂₂(OH)₂–Ca₂Fe²⁺₅Si₈O₂₂(OH)₂). In this context, it is shown that the intensity and especially the number of the IR bands in the ν(OH) region could serve as a tool for exact mineral identification. Namely, it is based on the presence of different Y cations in various octahedral sites (M1 and M3), which is manifested by different spectral view. On the other hand, the expressed similarities in the 1300–370 cm⁻¹ (IR) and 1200–100 cm⁻¹ regions (Raman) of the spectra are observed due to their common structural characteristics (double chains of SiO₄ tetrahedra). Thus, the bands in this region are tentatively prescribed mostly to the vibrations of the SiO₄ tetrahedra. The results of our study are compared with the corresponding literature data for the analogous mineral species originating all over the world.     

Infrared and Raman spectra of magnesium ammonium phosphate hexahydrate (struvite) and its isomorphous analogues. IX: Spectra of protiated and partially deuterated cubic magnesium caesium phosphate hexahydrate

Infrared and Raman spectra of cubic magnesium caesium phosphate hexahydrate, MgCsPO₄·6H₂O (cF100), and its partially deuterated analogues were analyzed and compared to the previously studied spectra of the hexagonal analogue, MgCsPO₄·6H₂O (hP50). The vibrational spectra of the cubic and hexagonal dimorphic analogues are similar, especially in the regions of HOH stretching and bending vibrations. In the difference IR spectrum of the slightly deuterated analogue (<5% D), one distinctive band appears at 2260 cm⁻¹ with a small shoulder at around 2170 cm⁻¹, but only one band is expected in the region of the OD stretchings of isotopically isolated HDO molecules. The small weak band could possibly result from second-order transitions (a combination of HDO bending and some libration of the same species) rather than statistical disorder of the water molecules. By comparing the IR spectra in the region of external vibrations of water molecules of the protiated compound recorded at RT (room temperature) and at LNT (liquid nitrogen temperature) and those in the series of the partially deuterated analogues, it can be stated with certainty that the bands at 924 and 817 cm⁻¹ result from librations of water molecules, rocking and wagging respectively. And the band at 429 cm⁻¹ can be safely attributed to a stretching Mg–O_w mode. In the ν₃(PO₄) and ν₄(PO₄) region in the infrared spectra, one band in each is observed, at 995 and 559 cm⁻¹, respectively. In the region of the ν₁ modes, in the Raman spectrum of the protiated compound, one very intense band was observed at 930 cm⁻¹ which is only insignificantly shifted to 929 cm⁻¹ in the spectrum of the perdeuterated compound. The band at 379 cm⁻¹ in the Raman spectrum could be assigned to the ν₂(PO₄) modes. With respect to the phosphate ion vibrations, the comparison between the two polymorphic forms of MgCsPO₄·6H₂O and their deuterated compounds shows that ν₁(PO₄) and ν₃(PO₄) appear at lower wavenumbers in the cubic phase than in the hexagonal phase. These data are in full agreement with the lower repulsion potential at the cubic lattice sites compared with that for the hexagonal lattice sites.     

Synthesis of rigid and C2-symmetric 18-crown-6 type macrocycles bearing diamide–diester groups: enantiomeric recognition for α-(1-naphthyl)ethylammonium perchlorate salts

A series of rigid and chiral C₂-symmetric 18-crown-6 type macrocycles (S,S)-4, (S,S)-5, (S,S)-6 and (R,R)-2 bearing diamide–ester groups were synthesized. The binding properties of these macrocycles were examined for α-(1-naphthyl)ethylammonium perchlorates salts by an ¹H NMR titration method. Taking into account the host employed, important differences were observed in the K_a values of (R)- and (S)-enantiomers of guests for macrocycles (S,S)-4 and (S,S)-6, K_S/K_R = 3.6, and K_S/K_R = 0.1 (K_R/K_S = 10.3) ΔΔG = 3.19 and ΔΔG = ?5.77 kJ mol^?1, respectively. The results indicated excellent enantioselectivity of macrocyclic (S,S)-6 towards the enantiomers of α-(1-naphthyl)ethylammonium perchlorate salts.     

A new luminescent sulfate bridged dimeric copper(II) complex with DNA binding and SO2 fixation ability: Synthesis and structure

New luminescent mononuclear and dinuclear copper(II) (S = 1/2) complexes [Cu(HL)(H₂O)₂](ClO₄)₂ (1a) and [Cu₂(HL)₂(μ-SO₄)₂]·2H₂O (1b) were synthesized with the acyclic tridentate pyridine-2-carboxaldehyde-2-pyridylhydrazone ligand, HL (1). Interestingly, the mononuclear complex 1a can be converted into the disulfate bridged dimeric copper(II) complex 1b by passing freshly prepared SO₂ through the basic medium. On excitation at 290 nm, the ligand fluoresces at 364 nm due to an intraligand ¹(π–π1) transition. Upon complexation with copper(II), the emission peak is slightly blue shifted (356 nm, F/F₀ 0.76 for 1a and 354 nm, F/F₀ 0.89 for 1b) with a little quenching in the emission intensity. The association constants (K_ass (5.06 ± 0.004) × 10⁴ for 1a and K_ass (5.46 ± 0.006) × 10⁴ for 1b at 298 K) and the thermodynamic parameters have been determined by UV–Vis spectroscopy. The molecular structure of the complex 1b (Cu?Cu 4.456 Å) has been determined by single crystal X-ray diffraction studies. The complex 1b exhibits a strong interaction towards DNA as revealed from the K_b (intrinsic binding constant) 6.3 × 10⁴ M^?1 and K_sv (Stern–Volmer quenching constant) 2.93 values.     

Determination of thermodynamic properties of Na2S using solid-state EMF measurements

To obtain reliable thermodynamic data for Na₂S(s), solid-state EMF measurements of the cell Pd(s)|O₂(g)|Na₂S(s), Na₂SO₄(s)|YSZ| Fe(s), FeO(s)|O₂(g)_ref| Pd(s) were carried out in the temperature range 870 < T/K < 1000 with yttria stabilized zirconia as the solid electrolyte. The measured EMF values were fitted according to the equation E_fit/V (±0.00047) = 0.63650 − 0.00584732(T/K) + 0.00073190(T/K) ln (T/K). From the experimental results and the available literature data on Na₂SO₄(s), the equilibrium constant of formation for Na₂S(s) was determined to be lg K_f(Na₂S(s)) (±0.05) = 216.28 − 4750(T/K)⁻¹ − 28.28878 ln (T/K). Gibbs energy of formation for Na₂S(s) was obtained as Δ_fG^∘(Na₂S(s))/(kJ · mol⁻¹) (±1.0) = 90.9 − 4.1407(T/K) + 0.5415849(T/K) ln (T/K). By applying third law analysis of the experimental data, the standard enthalpy of formation of Na₂S(s) was evaluated to be Δ_fH^∘(Na₂S(s), 298.15 K)/(kJ · mol⁻¹) (±1.0) = −369.0. Using the literature data for C_p and the calculated Δ_fH^∘, the standard entropy was evaluated to S^∘(Na₂S(s), 298.15 K)/(J · mol⁻¹ · K⁻¹) (±2.0) = 97.0.     

Thermoluminescence and photoluminescence study on 150 MeV proton beam irradiated K2Ca2(SO4)3:Eu phosphor

This paper investigates the thermoluminescent response of K₂Ca₂(SO₄)₃:Eu prepared by solid state diffusion method, to 150 MeV proton beams. The structural confirmation of the sample was done using the XRD technique revealing the polycrystalline nature and the formation of the compound. Samples in the form of pellets were irradiated by 150 MeV proton clinical beams with dose range of 0.1 Gy–300 Gy. Thermoluminescence glow curves of the irradiated samples were recorded and studied. It has been found that the phosphor shows a characteristic single peak at around 420 K. The TL response is linear in the range up to 200 Gy and then becomes supralinear for higher doses. Photoluminescence spectra of the sample have also been studied and reported. When the material was excited at 320 nm, single emission bands were observed at 436 nm, which can be assigned to the transitions between the lowest band of the 4f⁶5d configuration and the ground state ⁸S_7/2 of the 4f⁷ configuration of Eu²⁺ ion, confirming the incorporation of the impurity in the prepared sample. The excitation spectra of these samples at emission wavelength of 436 nm show a major band at 320 nm. The linear TL response of K₂Ca₂(SO₄)₃:Eu and low fading with good reusability, makes it a potential candidate to be used as a dosimeter for detecting the doses of proton beams for specific applications.     

Molar heat capacity and thermodynamic properties of 1-cyclohexene-1,2-dicarboxylic anhydride [C8H8O3]

The molar heat capacity C_p,m of 1-cyclohexene-1,2-dicarboxylic anhydride was measured in the temperature range from T=(80 to 360) K with a small sample automated adiabatic calorimeter. The melting point T_m, the molar enthalpy Δ_fusH_m and the entropy Δ_fusS_m of fusion for the compound were determined to be (343.46 ± 0.24) K, (11.88 ± 0.02) kJ · mol⁻¹ and (34.60 ± 0.06) J · K⁻¹ · mol⁻¹, respectively. The thermodynamic functions [H_(T)−H_(298.15)] and [S_(T)−S_(298.15)] were derived in the temperature range from T=(80 to 360) K with temperature interval of 5 K. The mass fraction purity of the sample used in the adiabatic calorimetric study was determined to be 0.9928 by using the fractional melting technique. The thermal stability of the compound was investigated by differential scanning calorimeter (DSC) and thermogravimetric (TG) technique, and the process of the mass-loss of the sample was due to the evaporation, instead of its thermal decomposition.     

Structure and magnetic properties of 3-oxyl-4,4,5,5-tetramethyl-2-oxoimidazolidin-1-olates

The paramagnetic salts (NH₃Bu^t)1 and [K(NH₂Bu^t)₂]1, where 1 is the 3-oxyl-4,4,5,5-tetramethyl-2-oxoimidazolidin-1-olate anion, were isolated for the first time in the individual state. The crystal structure of [K(NH₂Bu^t)₂]1 involves polymer chains formed by hydrogen bonding between anions 1 and [K₂(NH₂Bu^t)₄]²⁺ cation dimer fragments. The magnetic properties of [K(NH₂Bu^t)₂]1 are well described by the quasi-isolated dimer model with spins S = 1/2 coupled by weak exchange interactions via [K₂(NH₂Bu^t)₄]² fragments in polymer chains.     

Fourier transform and high sensitivity cw-cavity ringdown absorption spectroscopies of ozone in the 6030–6130 cm−1 region. First observation and analysis of the 3ν1+3ν3 and 2ν2+5ν3 bands

The absorption spectrum of ¹⁶O₃ has been recorded between 6030 and 6130 cm⁻¹ by Fourier Transform Spectroscopy (GSMA, Reims) and cw-cavity ringdown spectroscopy (LSP, Grenoble). The two new bands 3ν₁+3ν₃ and 2ν₂+5ν₃ centered at 6063.923 and 6124.304 cm⁻¹, respectively are observed and analyzed. Rovibrational transitions with J and K_a values up to 40 and 10, respectively, could be assigned. The rovibrational fitting of the observed energy levels shows that some rotational levels of the (303) and (025) bright states are perturbed by interaction with the (232), (510) and (124) dark states. The observed energy levels could be reproduced with a rms deviation of 5×10⁻³ cm⁻¹ using a global analysis based on an effective Hamiltonian including the five interacting states. The energy values of the three dark vibrational states provided by the fit are found in good agreement with theoretical predictions.The parameters of the resulting effective Hamiltonian and of the transition moment operator retrieved from the measured absolute line intensities allowed calculating a complete line list of 2035 transitions, available as Supplementary Material. The integrated band strengths are estimated to be 1.22×10⁻²⁴ and 3.15×10⁻²⁴ cm⁻¹/(mol cm⁻²) at 296 K for the 3ν₁+3ν₃ and 2ν₂+5ν₃ bands, respectively. A realistic error for these band strengths is 15% (see text).