Lambda-type doubling parameters for molecules in Π electronic states of triplet and higher multiplicity

Supersonic molecular beam samples of iridium monocarbide IrC and iridium mononitride IrN were generated using a laser ablation/reaction source and characterized using high resolution (Δν<30 MHz FWHM) laser induced fluorescence spectroscopy. This is the first identification of gaseous IrN. Numerous strong band systems in the 18 800 to 14 360 cm−1 spectral range were assigned as the (v′,0) progression of the A 1Π–X 1Σ+ band system of IrN. The (1,0) and (0,0) bands were analyzed to produce a set of fine and hyperfine parameters. The electric field induced effects on the R(0) line of these bands were analyzed to produce permanent electric dipole moments: A 1Π(v=0) 2.78(2) D, A 1Π(v=1) 2.64(2) D, X 1Σ+(v=0)=1.66(1) D. The (0,0) band of the D2 Φ7/2−X 2Δ5/2 system of IrC was recorded and analyzed to produce a set of fine and hyperfine parameters. The electric field induced effects on the R(2.5) branch feature were analyzed to produce permanent electric dipole moments: D 2Φ7/2(v=0) 2.61(6) D and X 2Δ5/2(v=0) 1.60(7) D. Plausible electronic configurations consistent with the experimental observations are given.

The optical and optical/stark spectrum of iridium monocarbide and mononitride

Fourier transform spectroscopy of VO: Rotational structure in the A4Π-X4Σ− system near 10 500 Å

The laser induced fluorescence spectrum of jet‐cooled CoC near 750 nm has been measured at high resolution following the reaction of laser‐ablated cobalt atoms with methane The X2Σ+ ground state of CoC is an unusually good example of Hund’s case (bβS) coupling Since Co has a nuclear spin I=7/2, each rotational level is split by the Fermi contact interaction into G=3 and G=4 components, where G=I+S; the splitting for N=0 is more than 05 cm−1 The X2Σ+ state begins to uncouple toward case (bβJ) with increasing rotation Transitions to various 2Π excited states occur in the region 13 000–14 500 cm−1; the most prominent of these (for which high resolution spectra have been recorded) lie at 13 079 cm−1 (2Π3/2) and 13 343 cm−1 (2Π1/2) The (bβS) coupling in the ground state produces some unexpected hyperfine intensity patterns, which have been studied in detail A very low‐lying 2Δi state, whose Ω=5/2 and Ω=3/2 components lie at 221 and 1173 cm−1, has been identified Laser excitation of the 2Π3/2–2Δ5/2 tran

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Electronic transitions of cobalt carbide, CoC, near 750 nm: A good example of case (bβS) hyperfine coupling

We present a complete analysis of the hyperfine structure of the MnH A 7Π–X 7Σ+ (0,0) band near 5680 A, studied with sub‐Doppler resolution by intermodulated fluorescence spectroscopy. Magnetic hyperfine interactions involving both the 55Mn (I=5/2) and 1H (I=1/2) nuclear spins are observed as well as 55Mn electric quadrupole effects. The manganese Fermi contact interaction in the X 7Σ+ state is the dominant contributor to the observed hyperfine splittings; the ΔF=0, ΔN=0, ΔJ=±1 matrix elements of this interaction mix the electron spin components of the ground state quite strongly at low N, destroying the ‘‘goodness’’ of J as a quantum number and inducing rotationally forbidden, ΔJ=±2 and ±3 transitions. The hyperfine splittings of over 50 rotational transitions covering all 7 spin components of both states were analyzed and fitted by least squares, allowing the accurate determination of 14 different hyperfine parameters. Using single electronic configurations to describe the A 7Π and X 7Σ+ states and Herm...

Elucidation of electronic structure by the analysis of hyperfine interactions: The MnH A 7Π–X 7Σ+ (0,0) band

Lines in the b3Σ+-a3II and c3Σ+-a3II systems of AlF show partially resolved hyperfine structure. This structure has been attributed to magnetic interactions involving the 27Al nucleus for which I = 5/2. About twenty unblended lines from the (0, 0) bands of the two systems have been analysed in detail, using a computer programme to simulate the profiles by calculating the frequencies and intensities of individual hyperfine transitions. For low values of the rotational quantum number, the lines show a simple triplet structure, which reflects the case (bβS) coupling in the 3Σ states. Analysis of these lines gives values for the Fermi contact parameters in the two states involved (bF = 0.049 cm-1 and 0.057 cm-1 in the b3Σ+ and c3Σ+ states respectively). As the rotational quantum number increases, the hyperfine patterns become less regular, indicating a departure from case (bβS) coupling in the 3Σ states and from case (aβ) coupling in the 3II state. By reproducing the details of these line-shapes, it has also proved possible to determine values for the electron spin-spin and spin-rotation parameters in the two 3Σ states: b3Σ+ λ = -0.025(10)cm-1 γ = 0.0000(3)cm-1 c3Σ+ λ = 0.00(1)cm-1 γ = 0.0015(10)cm-1 The experimental values for the Fermi contact parameter of AlF in the a3II and b3Σ+ states are well produced by a simple single configuration molecular orbital calculation but the value for the c3Σ state is rather larger than expected on this basis.

B. Rydh

Papers

An Analysis of Hyperfine Interactions in the Electronic Spectrum of AIF