Isotope shift relative

Our own calculations (B3LYP/6-311+G(d,p)) not only were in agreement with the published relative energies of T-10 and S-10 CA2) (A S-t = 4.3 kcal mol-1) but could also be used to show that the experimental IR spectrum fits better for T-10 than for S-10 and to identify carbene 7, which is also characterized by a strong UV absorption at 238/245 nm. Calculations also verify the isotopic shift of the diazo band in 9 compared to 15N2-9 (exp. —65 cm-1 calc. —73 cm-1). 

Chemical processes such as evaporation and condensation, precipitation of a mineral from a fluid phase, or diffusion can cause small changes in the relative abundances of the isotopes of the elements involved. These small isotopic shifts, which are typically a few parts in a thousand, are the basis for stable isotope geochemistry and cosmochemistry. 

Moreover, the tunability of the developed green laser and the rich density of I2 absorptions give a grid of frequency references at 1083 nm as we show in Fig. 9. It can be used for other frequency difference measurements, such as 3He hyperfine splittings and 3He-4He isotope shifts. This shift is large enough to allow a precise determination of the relative nuclear radii of these atoms, and it is also used to test QED corrections [23]. But, perhaps, the most important advantage of the new reference, is the possibility of absolute frequency measurements of... 

Laser-ablated La atoms were codeposited at 4 K with acetylene in excess Ar. The products La(C2H2), LaCCH2, HLaCCH, and La2(C2H2), were all characterized using IR spectroscopy. DFT calculations gave calculated vibrational frequencies, relative absorption intensities, and isotopic shifts that supported the identification of these molecules from the matrix IR... 

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