Experimental intensity and lineshape parameters of the oxygen A-band using frequency-stabilized cavity ring-down spectroscopy

Line intensities, self- and air-broadened linewidths, pressure-induced shifts, and collisional narrowing coefficients were measured from 2 ? J′ ? 32 in the P branch of the O₂A-band (12 975-13110 cm⁻¹) utilizing Galatry line profiles. Spectra were recorded using the frequency-stabilized cavity ring-down spectrometer located at NIST, Gaithersburg, MD with a spectral resolution <0.0001 cm⁻¹ and noise-equivalent absorption coefficient of 6 × 10⁻⁸ m⁻¹ Hz^−1/2. Line intensities, obtained from calibrated gas samples for 2 ? J′ ? 32, are ∼1% lower than the values in current spectroscopic databases. At higher J (18 ? J′ ? 32), the measured air- and self- broadened half widths are up to 20% lower than the extrapolated values given in HITRAN 2004, while corresponding half-widths for 2 ? J′ ? 15 are in better agreement. Available self-broadened half widths are fitted to empirical expressions with an rms of 0.8%. We discuss the implications of our results for accurate remote sensing of surface pressure and photon path length distributions.     

Oxygen broadening parameters of water vapor: 1212-2136 cm

Oxygen-broadened half-widths and pressure induced frequency shifts of water vapor were measured in the (0 1 0)-(0 0 0) band between 1212 and 2136 cm⁻¹. Over 400 observations were obtained at 0.0054 cm⁻¹ spectral resolution using a Fourier transform spectrometer at the Kitt Peak National Observatory. The observed width coefficients ranged from 0.0057 to 0.0718 cm⁻¹/atm and the shift coefficients fell between 0.0042 and −0.0169 cm⁻¹/atm. Previous measurements of N₂- and air-broadening of H₂O by the first author over this spectral range were included in the analysis to compute air-broadening coefficients with comparisons to the observed values. The H₂O+O₂ measured half-widths are compared with previously measured values given in the available literature.     

Multispectrum analysis of CH4 from 4100 to 4635 cm: 1. Self-broadening coefficients (widths and shifts)

The Lorentz self-broadening (halfwidths) and self-induced pressure-shift coefficients were measured for the first time in the octad region of methane. All spectra were recorded at 0.011 cm⁻¹ resolution using the McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory on Kitt Peak, Arizona. ¹²C-enriched CH₄ gas samples at room temperature were used, and high signal-to-noise ratios of 2000:1 were achieved. The multispectrum nonlinear least squares fitting technique enabled us to fit simultaneously a total of 10 high-resolution laboratory absorption spectra consisting of six self-broadened and four air-broadened spectra. In this paper, we report the self-broadened widths and self-induced pressure shift coefficients for 1423 transitions belonging to five bands with a maximum J of 16. The numbers of measurements by bands are: 71 for ν₂ + 2ν₄, 202 for ν₁ + ν₄, 824 for ν₃ + ν₄, 58 for 2ν₂ + ν₄, and 268 for ν₂ + ν₃. The observed widths varied from 0.045 to about 0.090 cm⁻¹ atm⁻¹ at 296 K. The measured pressure-shift coefficients had values extending from about −0.020 to −0.005 cm⁻¹ atm⁻¹ at 298.3 ± 1.2 K. The results obtained for the broadening coefficients in the various bands were compared with each other and with measurements reported in the literature for other methane bands.     

Line mixing effects in the ν2 + ν3 band of methane

This study provides the first direct experimental measurements of the off-diagonal relaxation matrix element coefficients for line mixing in air-broadened methane spectra for any vibrational band and the first off diagonal relaxation matrix elements associated with line mixing for pure methane in the ν₂ + ν₃ band of ¹²CH₄. The speed-dependent Voigt profile with line mixing is used with a multispectrum nonlinear least squares curve fitting technique to retrieve the various line parameters from 11 self-broadened and 10 air-broadened spectra simultaneously. The room temperature spectra analyzed in this work are recorded at 0.011 cm⁻¹ resolution with the McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory, Kitt Peak, Arizona. The off-diagonal relaxation matrix element coefficients of ν₂ + ν₃ transitions between 4410 and 4629 cm⁻¹ are reported for eighteen pairs with upper state J values between 2 and 11. The observed line mixing coefficients for self broadening vary from 0.0019 to 0.0390 cm⁻¹ atm⁻¹ at 296 K. The measured line mixing coefficients for air broadening vary from 0.0005 to 0.0205 cm⁻¹ atm⁻¹ at 296 K.     

CO2-broadened water in the pure rotation and ν2 fundamental regions

The CO₂-broadened water coefficients (half-widths, line shifts, and temperature dependence of the widths) are predicted using a fully complex Robert-Bonamy formulation for the 937 allowed and forbidden perpendicular type transitions of (000)-(000) between 200 and 900 cm⁻¹ in order to facilitate atmospheric remote sensing of Mars and Venus. In addition, empirical Lorentz line widths and pressure-induced frequency-shifts of CO₂-broadened H₂¹⁶O are obtained at room temperature for 257 perpendicular transitions of the (010)-(000) fundamental. For this, calibrated spectra recorded at 0.0054 cm⁻¹ resolution are measured assuming Voigt line shapes. For transitions between 1287 and 1988 cm⁻¹ with rotational quanta up to J = 13 and K_a = 6, the widths vary from 0.045 to 0.212 cm⁻¹ atm⁻¹ at 300 K; the pressure-shifts are quite large and range from −0.0386 to +0.0436 cm⁻¹ atm⁻¹. For the (010)-(000) band, the RMS and mean observed and calculated differences for CO₂-broadened H₂O half-widths are 12% and −1.9%, respectively, while the RMS and mean ratios of the observed and calculated pressure-induced shift coefficients are 1.6 and 0.79, respectively. For pairs of transitions involving K_a = 0 and 1, such as 2_0 2 ← 3_1 3 and 3_1 3 ← 2_0 2, both the calculated and observed pressure induced shifts in positions are opposite in sign and often similar in magnitude. The data are too limited to characterize vibrational dependencies of the widths, however.     

Multispectrum analysis of CH4 in the ν4 spectral region: II. Self-broadened half widths, pressure-induced shifts, temperature dependences and line mixing

Accurate values for line positions, absolute line intensities, self-broadened half width and self-pressure-induced shift coefficients have been measured for over 400 allowed and forbidden transitions in the ν₄ band of methane (¹²CH₄). Temperature dependences of half width and pressure-induced shift coefficients were also determined for many of these transitions. The spectra used in this study were recorded at temperatures between 210 and 314 K using the National Solar Observatory's 1 m Fourier transform spectrometer at the McMath-Pierce solar telescope. The complete data set included 60 high-resolution (0.006-0.01 cm⁻¹) absorption spectra of pure methane and methane mixed with dry air. The analysis was performed using a multispectrum nonlinear least squares curve fitting technique where a number of spectra (20 or more) were fit simultaneously in spectral intervals 5-15 cm⁻¹ wide. In addition to the line broadening and shift parameters, line mixing coefficients (using the off-diagonal relaxation matrix element formalism) were determined for more than 50 A-, E-, and F-species transition pairs in J manifolds of the P- and R-branches. The measured self-broadened half width and self-shift coefficients, their temperature dependences and the line mixing parameters are compared to self-broadening results available in the literature and to air-broadened parameters determined for these transitions from the same set of spectra.     

Multispectrum analysis of the ν4 band of CH3CN: Positions, intensities, self- and N2-broadening, and pressure-induced shifts

A multispectrum nonlinear least-squares fitting technique was applied to measure accurate zero-pressure line center positions, Lorentz self- and nitrogen (N₂)-broadened half-width coefficients, and self- and N₂-pressure-induced shift coefficients for over 700 transitions in the parallel ν₄ band of CH₃CN near 920 cm⁻¹. Fifteen high-resolution (0.0016 cm⁻¹) laboratory absorption spectra of pure and N₂-broadened CH₃CN recorded at room temperature using the Bruker IFS 125HR Fourier transform spectrometer located at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, USA, were analyzed simultaneously assuming standard Voigt line shapes. Short spectral intervals containing manifolds of transitions from the same value of J were fitted together. In all, high-precision line parameters were obtained for P(44)-P(3) and R(0)-R(46) manifolds. As part of the analysis, quantum assignments were extended, and the total internal partition function sum was calculated for four isotopologs: ¹²CH₃¹²CN, ¹³CH₃¹²CN, ¹²CH₃¹³CN, and ¹³CH₃¹³CN. Measurements of N₂ broadening, self-broadening, N₂-shift, and self-shift coefficients for transitions with J up to 48 and K up to 12 were measured for the first time in the mid-infrared. Self-broadened half-width coefficients were found to be very large (up to ∼2 cm⁻¹ atm⁻¹ at 296 K). Ratios of self-broadened half-width coefficients to N₂-broadened half-width coefficients show a compact distribution with rotational quantum number in both the P and R branches that range from ∼4.5 to 14 with maxima near ∣m∣=24, where m=−J″, J″, and J″+1 for P, Q, and R lines, respectively. Pressure-induced shifts for N₂ are small (few exceed ±0.006 cm⁻¹ atm⁻¹ at 294 K) and are both positive and negative. In contrast, self-shift coefficients are large (maxima of about ±0.08 cm⁻¹ atm⁻¹ at 294 K) and are both positive and negative as a function of rotational quantum numbers. The present measured half-widths and pressure shifts in ν₄ were compared with corresponding measurements of rotational transitions.     

Collision induced absorption spectra of the fundamental band of D2 in binary mixtures D2-Kr at 298 K

The enhancement spectrum of the collision induced absorption of D₂ in its fundamental band region 2600-4000 cm⁻¹ in binary mixtures D₂-Kr was studied at 298 K for base densities of D₂ in the range 9-20 amagat and for partial densities of Kr in the range 7-120 amagat. The binary absorption coefficient of the band has been determined from the measured integrated absorption coefficient and found to be 3.9 × 10⁻³ cm⁻² amagat⁻². An analysis of the experimental spectrum was carried out by assuming appropriate line-shape functions and the half-width parameters δ₁, δ₂, δ_d and δ_c of the long range quadrupole, and of the short range overlap induced transitions have been determined. Good agreement was obtained between the recorded spectrum of the fundamental band and the synthetic profile.     

Variable-temperature Raman scattering study on anatase titanium dioxide nanocrystals

The temperature dependence of the Raman modes in anatase TiO₂ nanocrystals has been investigated over the temperature range 77-873 K. With increasing temperature, the frequency of the E_g mode at 639 cm⁻¹ shifts sublinearly to the lower frequencies, however, the frequency of the lowest-frequency E_g mode shifts sublinearly to the higher frequencies from 138 cm⁻¹ at 77 K to 152 cm⁻¹ at 873 K and the frequency of the B_1g mode at 397 cm⁻¹ increases firstly and attains a maximum near 350 K. The linewidth of all of the three modes increases linearly with increasing temperature. The anharmonic effects contribute a lot to the temperature dependence behavior of the frequency and linewidth of Raman modes in anatase TiO₂ nanocrystals.     

Air-broadened halfwidth and pressure shift coefficients of CO2 bands: 4750-7000 cm

Previously we obtained self-broadened halfwidth and self-induced shift coefficients at room temperature for 15 near infrared CO₂ bands between 4750 and 7000 cm⁻¹ [R.A. Toth, L.R. Brown, C.E. Miller, V.M. Devi, D.C. Benner, J. Mol. Spectrosc., 239 (2006) 243-271]. The present study expands our work on the near infrared line parameters of CO₂ to include air broadening coefficients. Here we report nearly 400 air-broadened half width and air-induced pressure shift coefficients spanning 11 different CO₂ vibrational bands in the 4750-7000 cm⁻¹ region. Retrievals have been performed using Voigt line profiles over three distinct spectral intervals: (a) 4750-5200 cm⁻¹, covering the 20011 ← 00001, 20012 ← 00001, and 20013 ← 00001 Fermi Triad and three associated hot bands 21111 ← 01101, 21112 ← 01101, 21113 ← 01101; (b) 6100-7000 cm⁻¹, covering the 30011 ← 00001, 30012 ← 00001, 30013 ← 00001 and 30014 ← 00001 Fermi Tetrad; (c) near 6950 cm⁻¹ for the 00031 ← 00001 overtone band. The air-broadened halfwidth and air-induced pressure shift coefficients have been modeled with empirical expressions and compared to other measurements available in the literature.     

Measurements of positions, strengths and self-broadened widths of H2O from 2900 to 8000 cm: line strength analysis of the 2nd triad bands

High-resolution spectra of H₂O were recorded with a Fourier-transform spectrometer covering H₂O transitions from 2900 to 8000 cm⁻¹. Over 13,000 absorptions were measured to determine line positions, strengths and self-broadened half-width coefficients. The H₂ ¹⁶O line strengths of the (0 3 0)-(0 1 0), (1 1 0)-(0 1 0), (0 1 1)-(0 1 0) and (0 3 0)-(0 0 0), (1 1 0)-(0 0 0), (0 1 1)-(0 0 0) bands were fitted to a quantum mechanical model which involves the interactions between the (0 3 0), (1 1 0), and (0 1 1) vibrational states. Also fitted were experimental strengths of the hot bands; (1 2 0)-(0 1 0) and (0 2 1)-(0 1 0). The model includes 14 dipole matrix elements for B- and A-type transitions. The measured line positions were used along with hot water emission measurements (for the (0 3 0), (0 4 0), and (0 5 0) states of H₂ ¹⁶O) in an analysis to obtain high-accuracy energy level values in the (0 3 0), (1 1 0), (0 1 1), (0 4 0), (1 2 0), (0 2 1), (2 0 0), (1 0 1), (0 0 2), and (0 5 0) vibrational states of H₂ ¹⁶O and the (1 1 0) and (0 1 1) states of H₂ ¹⁷O. Also included were measurements and analysis of self-broadened half-widths for over 4700 absorptions between 4405 and 7729 cm⁻¹. The results from this investigation provide new information for the noted H₂ ¹⁷O bands and present a more accurate representation of the measured H₂ ¹⁶O bands.     

The absorption spectrum of phosphine (PH3) between 2.8 and 3.7 μm: Line positions, intensities, and assignments

Over 8000 line positions and intensities of phosphine (PH₃) at 3 μm have been measured at 0.0115 cm⁻¹ resolution with the McMath-Pierce Fourier Transform spectrometer at Kitt Peak. The observed line intensities ranged from 4.13 × 10⁻⁶ to 4.69 × 10⁻² cm⁻² atm⁻¹ at 296 K, for line positions between 2724.477 and 3601.652 cm⁻¹. This region spans eight interacting vibrational states: 3ν₂ (2940.8 cm⁻¹), 2ν₂ + ν₄ (3085.6 cm⁻¹), ν₂ + 2ν₄ (3214.9 cm⁻¹), ν₁ + ν₂ (3307.6 cm⁻¹), ν₂ + ν₃ (3310.5 cm⁻¹), 3ν₄ (∼3345 cm⁻¹), ν₁ + ν₄ (3426.9 cm⁻¹), and ν₃ + ν₄ (3432.9 cm⁻¹). Assignments have been determined for all the bands except 3ν₄ (a weak band in a highly congested area) for a total of 4232 transitions. The total integrated intensity for this region is 5.70 cm⁻² atm⁻¹ near 296 K, and assigned lines account for 79% of the observed absorption. The two strongest bands in the region are ν₁ + ν₄ and ν₃ + ν₄ with band strengths at 296 K of 1.61 and 2.01 cm⁻² atm⁻¹, respectively. An empirical database of PH₃ line parameters (positions, intensities, and assignments) is now available. Lower state energies (corresponding to assignments from this study) and line widths from the literature are included; default values are used for unassigned features.     

Near infrared spectroscopy of carbon dioxide I. OCO line positions

High-resolution near-infrared (4000-9000 cm⁻¹) spectra of carbon dioxide have been recorded using the McMath-Pierce Fourier transform spectrometer at the Kitt Peak National Solar Observatory. Some 2500 observed positions have been used to determine spectroscopic constants for 53 different vibrational states of the ¹⁶O¹²C¹⁶O isotopologue, including eight vibrational states for which laboratory spectra have not previously been reported. Calibration by simultaneous use of CO near 4200 cm⁻¹ and C₂H₂ near 6500 cm⁻¹ provides absolute line position accuracies of 6.0 × 10⁻⁵ cm⁻¹ (RMS) for strong, isolated transitions throughout the observed range. Fits with RMS errors <3.8 × 10⁻⁵ cm⁻¹ have been obtained for the 20013 ← 00001, 20012 ← 00001, and 20011 ← 00001 bands, RMS errors <6 × 10⁻⁵ cm⁻¹ have been obtained for the 30014 ← 00001, 30013 ← 00001, 30012 ← 00001, and 00031 ← 00001 bands, and RMS errors <5 × 10⁻⁴ cm⁻¹ for even the weakest fitted bands. This work reduces CO₂ near-infrared line position uncertainties by a factor of 10 or more compared to the 2000 HITRAN line list, which has not been modified since the comprehensive work of Rothman et al. [J. Quant. Spectrosc. Rad. Transfer 48 (1992) 537]. The new line list satisfies the line position accuracies required for the next generation of CO₂ remote sensing instruments, improves the capability of solar-viewing spectrometers to retrieve precise column CO₂ measurements, and provides a secondary frequency standard in the near-infrared.     

Diode laser measurements of line strengths and collisional half-widths in the ν1 band of OCS at 298 and 200K

Absolute line strengths and self-broadened half-widths have been measured at 298 and 200 K for spectral lines ranging from J = 1 to 55 in the ν₁ band (860 cm^-1) of ¹⁶O¹²C³²S, using a tunable diode laser spectrometer. The vibrational transition moment (6.412 ± 0.16 × 10^-2D) as well as the absolute intensity (29.63±1.48 cm^-2-atm^-1 at 298 K), of the ν₁ band are determined from these line-strenght measurements. By applying two semi-classical impact theories of collisional broadening, we have obtained results for half-widths at 298 and 200 K which are significantly larger than the experimental data for |m|<50. However, the variation of the linewidths with temperature is well reproduced theoretically.     

Metal ion-molecule kinetics at combustion temperatures: The reaction of Ca with O2

The high-temperature photochemistry (HTP) technique, previously used for reactions of neutral species, has been adapted to the study of atomic metal ion-molecule reactions. Ca⁺ ions were generated by 193 nm multi-photon photolysis of calcium acetyl acetonate and its pyrolysis fragments. The relative ion concentrations were monitored by laser-induced fluorescence at 393.4 nm. Ar was used as the bath gas. The data for the Ca⁺ + O₂ + M → CaO₂⁺ + M association reaction (1) are fitted by k₁(907-1425 K) = 3.5 × 10⁻³² exp(+3161 K/T) cm⁶ molecule⁻² s⁻¹. Combining with an approximate k₁(296 K) value in the literature leads to k₁(296-1425 K) = 5.8 × 10⁻²² (T/K)^−2.9 exp(−601 K/T) cm⁶ molecule⁻² s⁻¹. Over much of the observed temperature range reaction (1) has much smaller rate coefficients than the corresponding neutral Ca association reaction. Reaction (1) is shown to behave very similarly to the O₂ association reaction with neutral K atoms, with which Ca⁺ is iso-electronic. This suggests that the initial step is ion-pair complex formation of the superoxide Ca²⁺(O₂)⁻, which is also consistent with results from density functional calculations. The k₁ values are rationalized via Troe’s unimolecular formalism, which leads to good accord with the experiments.     

Preliminary analysis of CH3D from 3250 to 3700 cm

The infrared spectrum of CH₃D from 3250 to 3700 cm⁻¹ was studied for the first time to assign transitions involving the ν₂ + ν₃, ν₂ + ν₅, ν₂ + ν₆, ν₃ + 2ν₆ and 3ν₆ vibrational states. Line positions and intensities were measured at 0.011 cm⁻¹ resolution using Fourier transform spectra recorded at Kitt Peak with isotopically enriched samples. Some 2852 line positions (involving over 900 upper state levels) and 874 line intensities were reproduced with RMS values of 0.0009 cm⁻¹ and 4.6%, respectively. The strongest bands were found to be ν₂ + ν₃ at 3499.7 cm⁻¹ and ν₂ + ν₆ at 3342.5 cm⁻¹ with integrated strengths, respectively, of 8.17 × 10⁻²⁰ and 2.44 × 10⁻²⁰ (cm⁻¹/molecule · cm⁻²) at 296 K (for 100% CH₃D). The effective Hamiltonian was expressed in terms of irreducible tensor operators and adapted to symmetric top molecules. Its present configuration in the MIRS package permitted simultaneous consideration of the four lowest polyads of CH₃D: the Ground State (G.S.), the Triad from 6.3 to 9.5 μm, the Nonad from 3.1 to 4.8 μm and now the Enneadecad (19 bands) from 2.2 to 3.1 μm. The CH₃D line parameters for this interval were calculated to create a new database for the 3 μm region.     

Temperature dependence of the absorption spectrum of CH4 by high resolution spectroscopy at 81 K: (II) The icosad region (1.49-1.30 μm)

The high resolution absorption spectrum of methane has been recorded at liquid nitrogen temperature by differential absorption spectroscopy between 6717 and 7351 cm⁻¹ (1.49-1.36 μm) using a cryogenic cell and a series of distributed feed back (DFB) diode lasers. The investigated spectral region corresponds to the very congested low energy part of the icosad for which the HITRAN database provides neither rovibrational assignments nor the lower state energies. The positions and strengths at 81 K of 9389 transitions were obtained from the spectrum analysis. The minimum value of the measured line intensities (at 81 K) is on the order of 10⁻²⁶ cm/molecule. From the variation of the line strength between 81 K and 296 K, the low energy values of a total of 4646 transitions were determined. They represent 79.4% and 68.4% of the total absorbance in the region at 81 and 296 K, respectively, and include 28 transitions assigned to the ν₂+4ν₄ band near 6765 cm⁻¹. The reliability of the method based on the association of lines with coinciding centers in the 81 K and 296 K spectra is discussed. The results of the present analysis have been combined with previously analyzed high energy part of the icosad dominated by the ν₂+2ν₃ band near 7510 cm⁻¹. The line list for the whole icosad (6717-7655 cm⁻¹) consists of 12 865 transitions at 81 K.     

One-magnon light scattering and spin-reorientation transition in epitaxial BiFeO3 thin films

Raman scattering from one-magnon excitation has been observed for the first time in epitaxial BiFeO₃ thin films grown on (1 1 1) SrTiO₃ substrates. The intensities and the frequency of the magnon mode at 18.9 cm⁻¹ (M₁) showed a discrepancy at the characteristic temperatures of ∼140 and 200 K and the magnon mode at 27.9 cm⁻¹ (M₂) disappeared at ∼200 K suggesting spin-reorientation (SR) transition in the epitaxial BFO film. The dc susceptibility measurement showed a large discrepancy near these two temperatures evidently elucidating the spin-reorientation transition mechanism. The partial spectral weight of the magnon modes is believed to be transferred to the lowest phonon mode appearing at 72.8 cm⁻¹ and higher magnon mode M₂ disappearing near 200 K reveal magnon-phonon coupling near to SR transition.     

CW-cavity ring down spectroscopy of the ozone molecule in the 6625-6830 cm region

The absorption spectrum of ozone, ¹⁶O₃, has been recorded by CW-cavity ring down spectroscopy in the 6625-6830 cm⁻¹ region. The typical sensitivity of these recordings (α_min ∼ 3 × 10⁻¹⁰ cm⁻¹) allows observing very weak transitions with intensity down to 2 × 10⁻²⁸ cm/molecule. 483 and 299 transitions have been assigned to the 2ν₁ + 3ν₂ + 3ν₃A-type band and to the 2ν₁ + 4ν₂ + 2ν₃B-type band, respectively, which are the highest frequency bands of ozone recorded so far under high resolution. Rovibrational transitions with J and K_a values up to 46 and 12, respectively, could be assigned. Despite well-known difficulties to correctly reproduce the energy levels not far from the dissociation limit, it was possible to determine the parameters of an effective Hamiltonian which includes six vibrational states, four of them being dark states. The line positions analysis led to an rms deviation of 8.5 × 10⁻³ cm⁻¹ while the experimental line intensities could be satisfactorily reproduced. Additional experiments in the 5970-6021 cm⁻¹ region allows detecting the (233) ← (010) hot band reaching the same upper state as the preceding cold band. From the effective parameters of the (233) state just determined and those of the (010) level available in the literature, 329 transitions could be assigned and used for a further refinement of the rovibrational parameters of the effective Hamiltonian leading to a value of 7.6 × 10⁻³ cm⁻¹ for the global rms deviation. The complete list of the experimentally determined rovibrational energy levels of the (233), (242), and (520) states is given. The determined effective Hamiltonian and transition moment operators allowed calculating a line list (intensity cut off of 10⁻²⁸ cm/molecule at 296 K), available as Supplementary material for the 6590-6860 and 5916-6021 cm⁻¹ regions. The integrated band strength values are 1.75 × 10⁻²⁴ and 4.78 × 10⁻²⁵ cm/molecule at 296 K for the 2ν₁ + 3ν₂ + 3ν₃A-type band and to the 2ν₁ + 4ν₂ + 2ν₃B-type band, respectively, while the band intensity value of the (233) ← (010) is estimated to be 1.03 × 10⁻²⁴ cm/molecule.     

Dynamics of the charge transferred states relevant to magnetic phase transition in rubidium manganese hexacyanoferrate

Photoinduced charge transfer dynamics in the photomagnetic material RbMn[Fe(CN)₆], which exhibits a magnetic phase transition with a large hysteresis loop (230-300 K), has been investigated by observing the CN⁻ stretching modes, which are sensitive to the valences of the adjacent transition metal ions. Mid-infrared transient absorption measurements were performed between 2013 and 2179 cm⁻¹ to observe the transient and persistent products. The sample in the high-temperature phase was excited by 400 nm laser pulses at the ligand to metal charge transfer band near the high-temperature end of the hysteresis loop. Bleach of the Fe³⁺-CN⁻-Mn²⁺ band representing a decrease of the high-temperature phase and increases of the Fe²⁺-CN⁻-Mn³⁺ and Fe²⁺-CN⁻-Mn²⁺ bands were observed in picosecond time region, indicating a transient production of charge transferred states.