Overlapping B3Π0u ← X1Σ g/+ and 1Π1u ← X1Σ g/+ non-radiative characteristic of Br2 vapour in the wavelength region 505–541 nm

The vibronic vapour phase photoacoustic spectrum of Br₂ in the wavelength region 505–541 nm (19796–18480 cm⁻¹) has been recorded using microphone as well as pump-probe method. Discrete vibronic bands superimposed on a monotonically increasing continuum background towards the dissociation limit results from the overlapping B ³Π _0u ^/+ ← X ¹Σ _g ^/+ and ¹Π_1u ← X ¹Σ _g ^/+ electronic transitions. Vibronic bands originating from υ″=0 have been used to estimate the relative rate of non-radiative relaxation as a function of the excited state B ³Π_0u vibrational quantum number υ′. A comparison with the optical absorption spectroscopy of Br₂ leads to the identification of three broad spectral regions between 505 and 541 nm (19796 and 18480 cm⁻¹) on the basis of different non-radiative relaxation processes.     

Cesium fluoride mediated intramolecular conjugate-addition reactions of alpha sulfonyl ester to enones and alpha-chloroenones

Cesium fluoride is a useful catalyst to effect the intramolecular conjugate-addition of alpha-sulfonyl esters to enones; similar reaction with alpha-chloroenones provides fused cyclopropane adducts.     

Green route fast synthesis and characterization of chemical bath deposited nanocrystalline ZnS buffer layers

Zinc sulphide (ZnS) thin films are deposited using chemical bath deposition method on the glass substrates in an aqueous alkaline reaction bath of zinc acetate and thiourea along with non-toxic complexing agent tri-sodium citrate at 95 °C. The results show noteworthy improvement in the growth rate of the deposited ZnS thin films and thickness of the film increases with the deposition time. From X-ray diffraction patterns, it is found that the ZnS thin films exhibit hexagonal polycrystalline phase reflecting from (101) and (0016) planes. The high resolution transmission electron microscopy studies confirmed the formation of hexagonal phase from the d-value calculation which was 0.3108 nm. X-ray photoelectron spectroscopy reveals that the Zn–S bonding energy is at 1022.5 and 162.1 eV for Zn 2p_3/2 and S 2p_1/2 states, respectively. Field emission scanning electron microscopy study shows that deposited thin films are highly uniform, with thin thickness and completely free from large ZnS clusters which usually form in aqueous solutions. Atomic force microscopy investigates that root mean square values of the ZnS thin films are from 3 to 4.5 nm and all the films are morphologically smooth. Energy dispersive spectroscopy shows that the ZnS thin films are relatively stoichiometric having Zn:S atomic ratio of 55:45. It is shown by ultraviolet–visible spectroscopy that ～90% transmittance and ～10% absorbance for the ZnS films in the visible region, which is significantly higher than that reported elsewhere and the band gap energy of the ZnS films is found to be 3.76, 3.74, and 3.71 eV, respectively.     

Interface engineering of p-n heterojunction for kesterite photovoltaics:A progress review

Kesterite Cu2ZnSn(S,Se)4(CZTSSe)is considered one of the most promising thin-film photovoltaic(PV)technologies due to its bandgap tunability(1.0～1.5 eV)and high...     

Li+- and Ag+-cationized per-O-acetyl- and Per-O-benzyl-α-D-thioglycosides: a collision-induced decomposition study

The collision-induced decompositions of the [M + Li]⁺ and [M + Ag]⁺ ions of per-O-acetyl- and per-O-benzyl-α-D -thioglycosides having phenyl sulphide, phenyl sulphoxide and phenyl sulphone as the aglycone moieties were studied. The [M + Li]⁺ ion of the acetyl derivative of the phenylthioglucoside shows loss of AcOLi, whereas its [M + Ag]⁺ ion shows elimination of PhSAg. Their sulphoxide and sulphone derivatives lose the C(1) and C(2) substituents to form the glucal under both Li⁺ and Ag⁺ cationization conditions. The corresponding benzyl derivatives do not show the loss of metal. The formation of glucal leads to ring fragmentation by retro-Diels-Alder reaction in the ring-activated benzyl derivatives.     

Torsional effects in the baeyer-villiger oxidation

The regioselectivity in the Baeyer-Villiger oxidation of tetracyclic ketones 1A–C have been interpreted in terms of torsional effects.