High-resolution Emission Spectra Research Articles

X-Ray structural and photoluminescence spectroscopic investigation of the europium octamolybdate polymer Eu2(H2O)12[Mo8O27]·6H2O and intramolecular energy transfer in the crystalline lattice

Photoluminescence and intramolecular energy-transfer properties of Eu2(H2O)12[Mo8O27]·6H2O, 1 have been determined in connection with the crystal structure. The compound has been prepared by treating K2[MoO4] with Eu(NO3)3 in aqueous solution at pH 3.0 and isolated in a crystalline form with a belt structure. A single-crystal X-ray analysis [triclinic, space group P, a= 10.105(3), b= 12.006(5), c= 9.365(4)A, α= 122.59(3), β= 90.12(3), γ= 98.33(3)°, Z=1, Mo-Kα radiation, R= 0.063 for 4485 independent data with I > 3σ(I)] shows the cation to have the composition [Eu(H2O)6]3+. The latter is also bonded to one oxygen atom of each octahedron of an edge-sharing pair of MoO6 octahedra in the Mo8O27 anion, which is isostructural to the condensation polymer of the octamolybdate through one common oxygen atom. In addition, Eu3+ is linked by one oxygen atom belonging to the MoO6 octahedron in a neighbouring Mo7O27 unit, resulting in the formation of a tricapped trigonal-prismatic Eu(H2O)6O3 group (average Eu–O bond length 2.48 A). Luminescent transitions of both 5D0→7FJ and 5D1→7FJ for Eu3+ are observed upon photoexcitation of the O → Mo ligand-to-metal charge-transfer (l.m.c.t.) bands but the intramolecular energy transfer to the 5D1 level takes place predominantly from the O → Mo l.m.c.t. states at energies higher than 3.6 eV (ca. 5.8 × 10–19 J). The temperature dependence of the intramolecular energy transfer from the O → Mo l.m.c.t. states to Eu3+ indicates that the configuration of the Mo–O–Eu linkage (ca. 150°) allows hopping of a d1 electron to the EuO9 site due to thermally activated delocalization between MoO6 and EuO9 sites, which acts as a deactivation channel for the energy transfer from the O → Mo l.m.c.t. states to the emitting levels of Eu3+. Co-ordination of six aqua ligands leads to a low lifetime (0.17 ± 0.01ms) of the emitting state of 5D0 with a resultant decrease in the total quantum yields of the emission, arising from vibronic coupling of the 5D0 state with the vibrational states of high-frequency OH oscillators. The 7F1, 7F2, 7F3, 7F4, 5D1 and 5D2 crystal-field splittings for the C1 site of Eu3+ are estimated on the basis of the high-resolution emission and excitation spectra at 77 K. Vibronic lines belonging to the 7F0→5D2 and 7F1→6D1 transitions are observed in the excitation spectrum.

Emission spectra of iodine fluoride from a corona-excited supersonic jet discharge

High-resolution emission spectra of IF from a corona-excited supersonic jet discharge are presented. Six vibrational bands of the D'2-A'2 transition were rotationally analyzed for the first time, as well as four bands of the EO + -XO + transition. A study of the Ω-type doubling observed for the high-J rotational levels of D' has provided estimates for the relative energy differences between the electronic origins of the first-tier ion-pair states

Investigation of the rovibrational levels of the B3Πg state of 14N2 molecule above the dissociation limit N(4S) + N(4S) by Fourier transform spectrometry

Rotational analyses of vibrational levels of the B3Πg state, located above the dissociation threshold N(4S) + N(4S) were performed from a high-resolution emission spectrum recorded by Fourier transform spectrometry. Strong intensity perturbations were observed in the B3Πg vibrational levels ν′ = 13, 14, and 15.

Fourier transform emission spectroscopy at 13 μm: Vibration–rotation spectrum of SiS

The vibration–rotation emission spectrum of the high temperature molecule SiS was recorded with a Fourier transform spectrometer. The observation of a high resolution emission spectrum at 13 μ (750 cm−1) is unusual but we believe this technique is generally applicable to high temperature species. Seven bands (1–0 through 7–6) of the main isotopic form, 28Si32S, were observed along with three bands (1–0, 2–1, and 3–2) for each of the minor species, 29Si32S, 30Si32S, and 28Si34S. Mass-reduced Dunham parameters, including Watson’s correction due to the breakdown of the Born–Oppenheimer approximation, were derived from the data.

Observation of the spin-orbit components of the 3B 2g( 3A 2g) ground state in the system Ni 2+:MgF 2 by fluorescence line narrowing

Using a tunable narrow-band infrared laser, we demonstrate for the first time infrared-fluorescnece line narrowing in the system Ni 2+:MgF 2. High-resolution emission spectra were obtained by pumping the lowest spin-orbit component B 3 ( 3T 2g) (orthorhombic notation with octahedral notation in parentheses) of the 3T 2g multiplet and observing the B 3( 3T 2g)→B 1, A, B 2( 3A 2g) luminescent transitions at low temperature. By tuning the narrow-band laser over the B 3( 3T 2g) band, resonant and non-resonant fluorescence were obtained which narrowed with respect to the inhomogeneously broadened profile, and additional lines were observed. The spectra can be understood in terms of a simultaneous excitation of two different subsets of Ni 2+ ions which have their B 2( 3A 2g)→B 3( 3T 2g) and A( 3A 2g)→B 3( 3T 2g) transitions in resonance with the laser. The A( 3A 2g) and B 1( 3A 2g) spin-orbit components of the ground-state multiplet lie 1.9 cm −1 and 6.5 cm −1 above the B 2( 3A 2g) ground state, respectively, at 2 K.

Quantum-field-theoretical description of photoelectron emission spectra of high-Tc superconductors.

High-resolution photoelectron emission spectra of the superconducting phase of Bi-Sr-Ca-Cu-O crystals (see Imer {ital et} {ital al}., Phys. Rev. Lett. 62, 336 (1989)) show that occupied electron states exist in the BCS energy gap (see J. Bardeen, L. N. Cooper, and J. R. Schrieffer, Phys. Rev. 108, 1175 (1957)). This is easily explained by quantum field theory, when a new state vector is introduced to describe the electron system. A comparison of the theoretical results with the measured data shows quite excellent agreement.

Higher excited-state luminescence of Ni 2+ in various chloride lattices: CsCdCl 3, CsMgCl 3, CdCl 2 and MgCl 2

The higher excited-state luminescence properties of Ni 2+ in the title compounds are presented. We report the observation of novel emissions corresponding to the interexcited-state 3T 1g← 1T 2g and 1E g← 1T 2g (O h notation) transitions and show that the former transition can have important consequences concerning Ni 2+Ni 2+ cross relaxation in these systems. Low-temperature, high-resolution survey absorption and emission spectra are presented for Ni 2+:CsCdCl 3. Low-temperature, high-resolution 3T 1g← 1T 2g emission spectra are presented for each of the title compounds. Trigonal splittings of the 3T 1g and 3T 2g states can clearly be seen in the 3T 1g← 1T 2g and 3T 2g← 1T 2g emissions. We note that the relative intensities of emissions from the 1T 2g state seem to be inconsistent with spin selection rules.

Near-infrared emission bands of TeH and TeD

High-resolution emission spectra of TeH and TeD have been obtained in the region 4200 to 3600 cm −1 using a Bomem DA3.002 Fourier transform spectrometer. Analyses are given for the 0-0 and 1-1 bands of the X 2 2 Π 1 2 -X 1 2 Π 3 2 system of TeH and for the 0-0 band of TeD. In addition the 2-0 vibrational overtone bands of 130TeH, 128TeH, and 126TeH are observed and analyzed. Accurate molecular constants are given for the first time.

Calculation of excited-state distortions and the missing-mode effect from the high-resolution emission spectrum of trans-bis[bis(diphenylphosphino)ethane]bis(dinitrogen)tungsten

Calculation of excited-state distortions and the missing-mode effect from the high-resolution emission spectrum of trans-bis[bis(diphenylphosphino)ethane]bis(dinitrogen)tungsten

Stratospheric HBr mixing ratio obtained from far infrared emission spectra

Emission features of HBr isotopes have been identified in high‐resolution far‐infrared emission spectra obtained with a balloon‐borne Fourier transform spectrometer in the spring of 1979 at 32°N latitude. When six single‐scan spectra at a zenith angle of 93.2° were averaged, two features of HBr isotopes at 50.054 and 50.069 cm−1 were obtained with a signal‐to‐noise ratio of 2.5. The volume mixing ratio retrieved from the average spectrum is 2.0 × 10−11, which is assumed to be constant above 28 km, with an uncertainty of 35 percent. This stratospheric amount of HBr is about the same as the current level of tropospheric organic bromine compounds, 25 pptv. Thus, HBr could be the major stratospheric bromine species.

High resolution emission spectra of one second delayed fluorescence from chloroplasts

The first well resolved emission spectra of white light-illuminated spinach chloroplasts at room temperature show that one second delayed fluorescence occurs at 685 nm. We demonstrate that reabsorption of this delayed fluorescence induces the second (probably prompt) emission observed at 730 nm and which we identify with the photosystem I peripheral antenna system.

Spectroscopy and photodissociation dynamics of H2O: Time-dependent view

We present a study of H2O photodissociation dynamics in the first excited state. The absorption and emission spectra are calculated quantum mechanically using a time-dependent wave packet propagation technique. The excited state potential energy surface is obtained from ab initio data generated by Palma et al., while the ground state is a model by Reimers and Watts cast in a simple analytical form and constructed by fitting to infrared data. The variation of the transition dipole moment is taken into account by using an analytical functional form which is adjusted to fit the low resolution experimental emission spectrum. The calculated absorption spectrum is very similar to both the experimental one and results obtained with other methods. The high resolution emission spectrum is calculated for the first time and shows excellent agreement with the recently measured experimental spectrum by Hudson and co-workers. Dynamics on both the ground and excited states are examined.

Identification of Organic and Inorganic Activators of Photoluminescence in Calcite by Laser Microprobe Spectroscopy: ABSTRACT

High-resolution laser-excited emission spectra provide new evidence that organic activation of photoluminescence can be distinguished from trace-element activation in calcite. Ultraviolet (362 nm), blue-violet (454 nm), and green (514 nm) wavelengths of an argon ion laser were focused through a petrographic microscope to generate photoluminescence from 2 to 5-/mu/m spots. Emissions spectra from pristine, organic-rich red algal skeletons and synthetic calcite crystals spiked with manganese were measured by an ISA U-1000 spectrometer. Biogenic and synthetic calcites display distinctly different spectra. With shorter exciting wavelengths, emission spectra of biogenic calcite show a blue shift in peak maximum from 620 to 480 nm. Spectra of manganese-spiked synthetic calcite show no change in the 630-nm peak maximum with shorter exciting wavelengths. The spectral characteristics are consistent with the known photoluminescence emission of high molecular weight aromatic hydrocarbon compounds and manganese-bearing calcite, respectively. The absolute intensity of photoluminescence also shows a difference between biogenic and synthetic calcites. In biogenic calcite, the intensity increases with shorter excited wavelengths; the intensity under 362-nm excitation is five and one-half times stronger than that under 514-nm excitation. In the manganese-spiked calcite, the intensity decreases with shorter exciting wavelengths; the intensity under 514-nm excitation is five times stronger thanmore » that under 362-nm excitation. The emission patterns are consistent with the known absorbance spectra of aromatic hydrocarbons and manganese-bearing calcite. In conjunction, measurements of peak shift and intensity demonstrate that variable-wavelength laser excitation must be used to distinguish organic from inorganic photoluminescence activators in calcite.« less

Measurement of nighttime stratospheric N2O5 from infrared emission spectra

The mixing ratio profile of N2O5 has been inferred from high‐resolution emission spectra obtained with a balloon‐borne Fourier spectrometer (SIRIS). The observations were taken for the period from midnight to predawn on September 16, 1986 at 32° N latitude. The inferred volume mixing ratio from nighttime average spectra has a peak of ∼ 1.8 × 10−9 in the 32‐35 altitude range. The inferred mixing ratio is generally less than the theoretical predictions from a 1‐D model.

Retrieval of constituent mixing ratios from limb thermal emission spectra

An onion-peeling iterative, least-squares relaxation method to retrieve mixing ratio profiles from limb thermal emission spectra is presented. The method has been tested on synthetic data, containing various amounts of added random noise for O(3), HNO(3), and N(2)O. The retrieval method is used to obtain O(3) and HNO(3) mixing ratio profiles from high-resolution thermal emission spectra. Results of the retrievals compare favorably with those obtained by others.

High-resolution study of the [formula omitted] emission system of 80SeO

The b 0 +− X 2 1 and b 0 +− X 1 0 + subsystems of Seo were excited in a chemiluminescent reaction involving metastable O 2( 1 Δ g) molecules. High-resolution emission spectra were recorded with a Bomem interferometer. Rotational analyses were carried out for four bands of 80SeO, viz., 0-0, 1-1, 0–1, and 1–2. The following equilibrium constants were obtained: bO +, , B e = 0.4571873(7) cm -1, , α e = 0.0037059(9), , cm -1, , r e = 1.663325(1) A ̊ x 21, , B e = 0.4706269(5) cm -1, , α e = 0.0032737(6), , cm -1, , r e = 1.639403(1) A ̊ , W e = 915.59 cm -1, , W eX e = 4.56 cm -1 X 10 + B e = 0.47048 12(5) cm -1, , α e = 0.0032764(6), , cm -1, r e = 1.639657( 1) A ̊ , w.=915.10 cm -1, , W eX e = 4.57 cm -1, where the error limits are 3σ. From the analysis of the line intensities the ratio of the parallel and perpendicular transition moments, μ 0 μ 1 = −1.42 6 was derived.

One- and two-photon spectroscopy of the 3E g state of NaF:Cu+: Observation and analysis of vibronic fine structure

One- and two-photon laser excitation spectra of the 1A1g→3Eg transition of NaF:Cu+ are reported, these being the first direct observations of the lowest d9s excited state of Cu+ in an alkali halide host. The spin–orbit splitting of the 3Eg vibronic origin is directly measured, and can be compared with values inferred from studies of the temperature and magnetic field dependence of the emission lifetime. Clear vibrational progressions based on both spin–orbit origins are assigned to odd parity local modes of t1u symmetry. We also report high resolution emission spectra which reveal evidence of a corresponding local mode in the ground state with a fundamental frequency significantly higher than that observed in any of the d9s excited states. We model these spectroscopic data and those of the 1Eg and 1T2g states within the adiabatic approximation using three-parameter anharmonic vibrational potentials, evaluating the energies and wave functions by a variational procedure. Good fits are obtained for most spectroscopic features. Those features which are not accommodated by the adiabatic model potentials are accounted for by nonadiabatic vibronic coupling.

High resolution emission spectra of the 0–0, 0–1 and 0–2 bands ofE 1 Π-A 1 Π andB 1 Σ +-A 2 Π transitions in12C18O molecule

In the emission spectrum of the12C18O isotopic molecule the 0–0, 0–1 and 0–2 bands of twoE 1 Π-A 1 Π andB 1 Σ + transitions have been photographed at high resolution. After a rotational analysis of bands the following molecular constants have been calculated: (1) the rotational constantsB o andD o for the upperE 1 Π andB 1 Σ + states andB v ,D v for theA 1 Π state, (2) the reduced band originsc ov , for both transitions, (3) the Λ-doubling constants for theE 1 Π state, (4) the distances betweenv=0 levels in theE 1 Π,C 1 Σ + andA 1 Π states. Some molecular constants have been derived from the combinational analysis of bands which belong to theE 1 Π-A 1 Π andB 1 Σ +-A 1 Π and alsoE 1 Π-A 1 Π andC 1 Σ +-A 1 Π transitions. Strong perturbation of theA 1 Π state bye 3 Σ − nearby electronic state, observed in the 0–0 band ofB + Σ +-A 1 Π system has also been analysed.

The high-resolution emission spectrum of S 2 in the near infrared: The b1Σ g+- X3Σ g− system

Bands of the b 1Σ g +- X 3Σ g − system of S 2 have been excited in a discharge flow system by reacting ground state S 2 molecules with metastable O 2( 1Δ g) molecules. The 0-0, 0-1, and 1-1 bands have been recorded in emission with a Bomem interferometer, together with the 0-0 band of 32S 34S. The rotational structures of the bands are determined by magnetic dipole selection rules. Detailed analysis has yielded accurate values for the molecular constants of the b 1Σ g + and X 3Σ g − states. The rotational line intensities are well reproduced by the line strength formulae of Watson.

The Eu(III) ion as luminescent probe: Laser-spectroscopic investigation of the metal ion sites in an 18-crown-6 complex

The structure of [Eu(NO3)2(18-6)]3[Eu(NO3)6] has been probed by high-resolution excitation and emission spectra at 77 and 4.2 K. The compound contains centrosymmetric [Eu(NO3)6]3− ions with D2h, C2h, or Ci symmetry and three types of complex [Eu(NO3)2(18-6)]+ cations with D2 symmetry slightly distorted towards C2v. The luminescence spectra of Ln2Mg3(NO3)12 ⋅ 24H2O (Ln=Eu and La doped with 1% Eu) have also been recorded and are compared to the spectrum of the hexanitrato ion. The high-resolution study of the 5D0→7F1 transition at 4.2 K, both of polycrystalline samples and of monocrystals of the Eu-doped Gd complex, revealed that each metal site does not generate a single emission spectrum but, rather, a series of very similar spectra. These arise from molecules experiencing slightly different crystal field effects, that is, having slightly different conformations. The Eu(III) ion is therefore a quite sensitive luminescent probe responding to faint chemical differences often overseen in x-ray diffraction studies; it could be used to probe the conformational distribution of molecules in polycrystalline solids.