Infrared spectrum of formaldehyde: Coriolis interactions in the combination bands ν2 + ν6 and ν2 + ν3

A high-resolution infrared spectrum of H₂CO was measured in the range from 2600 to 3300 cm^?1. Vibration-rotation lines assigned to the combination bands ν₂ + ν₃ (a-type) and ν₂ + ν₆ (b-type) were analyzed as asymmetric-rotor bands by taking account of the Coriolis interactions among the ν₂ + ν₃, ν₂ + ν₆, and ν₂ + ν₄ states, though none of the ν₂ + ν₄ band lines have yet been definitely identified. The main results in cm^?1 units (with 2.5 times standard errors in the last digits given in parentheses) are: ν₀ = 3238.45(1), A - B?= 8.252(3), B?= 1.2053(2), and B - C = 0.1719 (assumed) for ν₂ + ν₃; ν₀ = 3000.10(1), A - B?= 8.125(46), B?= 1.2075(5), and B - C = 0.1693(14) for ν₂ + ν₆; and ν₀ = 2904.6(48), A - B?= 8.225(54), B?= 1.2023(20), and B - C = 0.1522 (assumed) for ν₂ + ν₄; the effective Coriolis interaction terms are: ξ_26,24^a = 10.10(3)cm^?1 and ξ_23,26^c = 0.96(3)cm^?1 under the assumption that ξ_23,24^b = 1.2841cm^?1. A second combination band 2ν₂ + ν₆ measured with lower resolution gave ν₀ = 4734.81(6)cm^?1.     

Instability of a periodically moving plate

The parametric instability of the in-plane motion of a rectangular plate of periodically varying length is investigated. The boundaries of the instability regions are found and plotted.     

Two-body hadronic decays of the 3.1 GeV resonance

Hadronic two body decays of the 3.1 GeV resonance were measured and the following branching ratios were obtained: Γ_π⁺_π^?/Γ_μμ <0.0046, Γ_K⁺_K^?/Γ_μμ <0.0084, and $\text{Γ}{}_{\mathrm{p}}\text{p}\text{/ Γ}{}_{\mathrm{\mu }}{}_{\mathrm{\mu \mu }}\text{= 0.036 ± 0.010}$ assuming the p$\text{p}$ decay distribution is ≈ + cos²θ.     

A new type of corrin synthesis

Work towards a synthesis of vitamin B₁₂ has inspired a new type of corrin synthesis. The key step is a light-induced 1,16-hydrogen transfer leading to an antarafacial (π→σ)-cycloisomerization of a seco-corrinoid metal complex. The construction of the seco-corrinoid ligand system is achieved by coupling monocyclic ring precursors in their enamide or enamine form through the methods of sulfide-contraction via oxidative coupling and of iminoester-enamine condensation.     

The a-type rotational spectrum of HNCS in the excited bending states

The microwave and millimeter wave spectra of HNCS in the three bending excited states, v₄ = 1, v₅ = 1, and v₆ = 1, have been measured. The ^qR₀, ^qR₁, and ^qR₂ branches for each of these three states and the ^qR₃ branch for the lowest excited state have been assigned. Effective rotational and centrifugal distortion constants have been determined for each vibrational and K_a-rotational sub-state. Two local resonances, caused by the Coriolis induced asymmetry interaction and a b-type Coriolis resonance, allow unambiguous confirmation of the assignment of the state v₆ = 1, the first excited state of the out-of-plane vibration.     

Simple components of group algebras Q[G] central over real quadratic fields

Let k be a real quadratic field, and $\text{U}$ a central division quaternion algebra over k. In this paper sufficient conditions are given to insure that $\text{U}$ appears in a simple component of the group algebra Q[G] of some finite group G over the rational field Q. In particular, when k is assumed to be Q(√2) or Q(√5), the necessary and sufficient conditions for $\text{U}$ to appear in some Q[G] are given.