Yukako Ohashi

MICROWAVE SPECTRUM OF METHYLENE FLUORIDE. CENTRIFUGAL DISTORTION AND MOLECULAR STRUCTURE.

Abstract The microwave spectra of CH2F2 and CD2F2 were investigated in detail to determine the centrifugal distortion constants: τaaaa = −2.3049 ± 0.0041, τbbbb = −0.06064 ± 0.00091, τcccc = −0.02653 ± 0.00071, T1 = 0.170 ± 0.012, and T2 = −0.03648 ± 0.00099 MHz for CH2F2 and τaaaa = −0.865 ± 0.011, τbbbb = −0.0530 ± 0.0017, τcccc = −0.0268 ± 0.0015, T1 = 0.036 ± 0.016, and T2 = −0.0327 ± 0.0018 MHz for CD2F2. The molecular structure determined using rotational constants of the four isotopic species is r( CH ) = 1.093 4 ± 0.003 A , r( CF ) = 1.357 4 ± 0.001 A , θ(∠HCH) = 113°40′ ± 10′, θ(∠FCF) = 108°19.0′ ± 3′.

The energy transfer mechanism in cis-dichloro and dibromobis(α, α′-dipyridyl)rhodium(III) complexes

The emission and absorption spectra of cis-dichlorobis(α-, α′-dipyridyl)-rhodium(III) chloride dihydrate and cis-dibromobis(α-, α′-dipyridyl)rhodium(III) bromide dihydrate were measured in microcrystals and in aqueous solutions. The emission spectra assigned as phosphorescence from the lowest triplet (3(dd∗)) excited state of the metal ion were found to shift toward higher frequencies with the increasing temperature. The emission decay and rise times were measured at 77°K and at room temperature with the following results: the decay time (μsec) was 45.2(77°K) and 11.6(R.T.) for the dichloro complex, and 26.5(77°K) and 2.39(R.T.) for the dibromo complex; the rise time (nsec) was 630(77°K) and 350(R.T.) for the dichloro complex, and 580 (77°K) and 340(R.T.) for the dibromo complex. The analysis of these data shows that energy transfer occurs from the singlet excited state of a ligand molecule (1(ππ∗)) to 3(dd∗) through the triplet excited state of a ligand molecule (3(ππ∗)).