The Raman spectrum of the symmetric stretching vibration (ν 1 ) of liquid carbon tetrachloride observed at 295 K and reported repeatedly over the last 80 years clearly shows four of the five more abundant isotopomers at 440-470 cm À1 . At the lower energy end of this spectrum, additional intensity due to isotopomeric contributions from the symmetric stretch for v = 1 → 2 (hotbands) partially overlaps the prominent v = 0 → 1 features, and accounts for about 18% of the integrated intensity at 295 K in agreement with theory. When these two patterns are modeled and subtracted from the experimental spectrum, a feature underlying almost exactly the C 35 Cl 4 (v = 0 → 1) band at 462.5 cm À1 becomes apparent. We propose that this feature is the ν 3 À ν 4 difference band. Observations at lower temperatures, and of the combination bands, and the polarized Raman spectra are consistent with this hypothesis.Additional supporting information may be found in the online version of this article at the publisher's web site.ν 3 À ν 4 difference band contribution to CCl 4 symmetric stretch mode

Raman spectroscopy is a powerful experimental technique, yet it is often missing from the undergraduate physical chemistry laboratory curriculum. Tetrachloromethane (CCl 4 ) is the ideal molecule for an introductory vibrational spectroscopy experiment and the symmetric stretch vibration contains fine structure due to isotopic variations of the molecule according to C 35 Cl x 37 Cl 4−x . We report simple theoretical predictions of the fine structure, calculation of Raman differential scattering cross sections, and discussion of the inherent asymmetry in the v 1 mode resulting from the different isotopes of chlorine. All calculations and discussion are appropriate for an undergraduate physical chemistry laboratory as either an independent dry lab or a supplement to a pre-existing vibrational spectroscopy lab.

In our previous article on CCl4 in this Journal, we presented an investigation of the fine structure of the symmetric stretch of carbon tetrachloride (CCl4) due to isotopic variations of chlorine in C35Clx 37Cl4–x . In this paper, we present an investigation of the contributions from both the v = 0 to v = 1 excitation and the v = 1 to v = 2 excitation. We report the calculation of spectral contributions from excited state vibrational transitions (hot bands). All calculations and discussion are appropriate for the undergraduate physical chemistry laboratory as either an independent dry lab or a supplement to a pre-existing vibrational spectroscopy lab.

In the last five years the size of the copper plated interconnect features for the logic and memory market has dropped below 30nm.  This decrease in size has forced plating chemistries to operate on copper seed that is often times either non continuous or has morphology that requires special tuning of the additives to create the bottom up phenomenon.  In the past, the traditional path of development led to the continued optimization of the organics additives (accelerators, suppressors, levelers) to help generate the void free fill in the plated interconnects while mostly fixing the inorganic concentrations.  A new approach to additive development is to optimize the organic additives in different electrolyte concentrations.  Traditionally, the copper chemical vendors were focused on the traditional 40g/L Cu2+, 10g/L sulfuric acid, 50ppm electrolyte formulation.  However, optimization of electrolytes can allow for a decrease in defectivity across the wafer.  This change in electrolyte formulation has sparked a new set of chemistry development at MLI to tune the organic chemistry to the electrolyte concentrations and also expand the understanding of the effect of electrolyte on the organic additives.  The current set of work aims at showing how acid affects the adsorption and desorption of a new advanced MLI suppressor.  This work starts with a basic understanding of how acid affects the plating bath with no suppressor present and then expands to show how this new suppressor is affected by the acid changes.  A surface adsorption and desorption model is then hypothesized based on the electrochemical signal.  The figure below outlines a typical adsorption result where an applied current of 10mA/cm2 is run while solution over the electrode is transitioned from one containing the electrolyte only to one containing the electrolyte and the MLI suppressor.  The two plots in the graph show the difference in the adsorption rate as a function of acid concentration.  One will note that the higher acid concentration shows a stronger steady state suppression and also a slower adsorption rate.  Experiments similar to these will be disclosed and the adsorption / desorption model discussed. Figure 1