A microwave-excited strontium-ion (λ430.5 nm) recombination laser

Laser oscillation on the 430.5 nm transition of Sr⁺, which replies on three-body electron-ion recombination for its excitation, has been achieved in a pulsed, selfheated, microwave-pumped discharge.     

A general route to the Streptomyces-derived inthomycin family: the first synthesis of (+)-inthomycin B

A concise, convergent and stereocontrolled synthesis of (+)-inthomycin B, based on the Stille coupling of a stannyl-diene with an oxazole vinyl iodide unit, is described. The asymmetric centre was introduced using the Kiyooka ketene acetal/amino acid-derived oxazaborolidinone procedure.     

Presence of lines in Raman spectra of living cells

Recently the validity of the Raman data from active cells and subsequent analysis has been questioned. We show here that this criticism is invalid.     

Nitrogen NMR studies on some fused ring N-heterocycles

¹⁵N and¹⁴N NMR data are reported for a number of fused ring N-heterocycles.¹⁴N line widths,¹⁵N-¹H couplings and nitrogen shielding additivity rales are used for¹⁵N signal assignments. The results obtained lead to some progress in the generalization of the effects of nitrogen-nitrogen interactions on nitrogen shieldings.     

Vacuum ultraviolet gain measurements in optically pumped LiYF4:Nd3+

 We present measurements of the net-induced gain on the 5d–4f transition at 186 nm in LiYF₄ : Nd³⁺ optically pumped by radiation from a molecular fluorine laser. It is found that for LiYF₄ : Nd³⁺, one of a series of potential continuously tunable VUV lasers, relatively strong excited-state absorption results in net-induced loss. The prospects for VUV laser operation being realised in other rare-earth-doped fluorides is discussed. Received: 4 March 1996/Revised version: 10 July 1996     

A quantitative N NMR investigation of tautomeric equilibria of two 1-hydroxybenzimidazoles

¹⁵N nuclear shielding data are used in a study of the tautomeric equilibria of two 1-hydroxybenzimidazoles. The nitrogen signal assignments are supported by INDO-S/SOS shielding calculations. The observation of the N-3 signal is shown to give a quantitatively reliable estimate of the position of equilibrium. In the unsubstituted 1-hydroxybenzimidazole the amount of the hydroxy from present in the equilibrium mixture is found to be proportional to the pK_a value of the solvent employed.