Spectroscopic quality potential

This paper addresses the question of what it means to have a spectroscopic quality potential energy surface. The literature of the last few years contains numerous references to spectroscopic quality ab initio molecular potentials, yet the definition of spectroscopic quality necessarily depends on the resolution of the experimental spectrum and the theoretical calculation. The accuracy of a molecular potential is perhaps better characterized by asking how well it reproduces experimental observables. This topic is explored by comparing the 1( 113/2) and X2 Yl rd potentials of the halogen monoxides determined from high-resolution spectroscopic studies with potentials computed using ab initio methods. The RKR potentials determined from spectroscopic data provide... 

For analytic experiments, silver wires (1 mm diameter), vitreous and graphite carbon rods (3 mm diameter Mersen spectroscopic quality) were used as working electrodes while the auxiliary electrode was a silicon plate (4x8 mm) with a large surface area (3 cm ). The potentials were measured with reference to a silicon plate immersed in the molten electrolyte. 

Despite the promising possibilities offered by the different types of nanoparticles, their routine use is still strongly limited by the very small number of commercially available systems and the limited amount of data on their reproducibility (in preparation, spectroscopic properties, and apphcation) and comparability (e.g., fluorescence quantum yields, stability) as well as on their potential for quantification. To date, no attempt has yet been published comparing differently functionalized nanoparticles from various sources (industrial and academic) in a Round Robin test, to evaluate achievable fluorescence quantum yields, and batch-to-batch variations for different materials and surface chemistries (including typical ligands and bioconjugates). Such data would be very helpful for practitioners and would present the first step to derive and establish quality criteria for these materials. 

An even simpler approach to relativity, for heavy elements, is to use effective core potentials (ECPs) to represent the core electrons, taking the potentials from various compilations in the literature that explicitly include relativistic effects in the generation of the ECPs. References to such ECPs are given by Dyall et al. [103]. These relativistic ECPs (RECPs) allow the inclusion of some relativistic effects into a nonrelativistic calculation. Since ECPs will be treated in detail elsewhere, we will not pursue this approach further here. We may note, however, that recent comparisons with Dirac-Fock calculations suggest that the main weakness in the RECPs is not the treatment of relativity but the quality of the ECPs themselves [103]. Different RECPs gave spectroscopic constants with a noticeable scatter, compared to Dirac-Fock, but the relativistic corrections (difference between an RECP and the corresponding ECP value) were fairly consistent with one another. 

The amount of scientific information contained in a licensing application may be vast (often exceeding 1000 pages). The pharmaceutical company presents evidence to show that every aspect of production of the medicinal product has been controlled and validated and is of an acceptable quality. The application starts with a description of the discovery chemistry for the new drug. This may be a chemical synthesis or an extraction of an active natural product from a plant or microorganism. Spectroscopic (e.g. NMR, MS, IR) and chromatographic (e.g. HPLC, GC) data are presented to show that the correct compound has been synthesised, and that by-products are identified and their levels controlled. The new chemical entity is then subjected to stability testing under accelerated conditions of heat, humidity, etc. to calculate shelf-life and rates of decomposition. Each decomposition product is identified and any potential toxicity is controlled. 

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