Substrate configuration

A schematic cross-section of a p-i-n a-Si H solar cell [11] is shown in Figure 72a. In this so-called superstrate configuration (the light is incident from above), the material onto which the solar cell structure is deposited, usually glass, also serves as a window to the cell. In a substrate configuration the carrier onto which the solar cell structure is deposited forms the back side of the solar cell. The carrier usually is stainless steel, but flexible materials such as metal-coated polymer foil (e.g. polyimid) ora very thin metal make the whole structure flexible [11]. 

In the substrate configuration the stainless steel carrier is coated with a Ag-ZnO bilayer in order to enhance the back reflection of the back contact see Figure 73 [11]. An increase in 7sc of about 50% was achieved by Banerjee and Guha [589] by using a textured Ag-ZnO bilayer, which further enhances the optical path length and consequently the absorption. As at this stage no [Pg.172]

As already mentioned, the dioxirane epoxidation of an alkene is a stereoselective process, which proceeds with complete retention of the original substrate configuration. The dioxirane epoxidation of chiral alkenes leads to diastereomeric epoxides, for which the diastereoselectivity depends on the alkene and on the dioxirane structure. A comparative study on the diastereoselectivity for the electrophihc epoxidants DMD versus mCPBA has revealed that DMD exhibits consistently a higher diastereoselectivity than mCPBA however, the difference is usually small. An exception is 3-hydroxycyclohexene, which displays a high cis selectivity for mCPBA, but is unselective for DMD . ... 

The nonstereospecific (using Zimmerman s definition) [108] nature of this reaction has been demonstrate by the use of stereoisomeric substrates which lead to oxetanes 114 in identical diastereomeric ratios. Another possibility for obtaining stereoisomerically pure oxetanes is the use of alkenes which simultaneously serve as quenchers for the carbonyl triplets, e.g., dienes. The photocycloaddition of acetone and 2-methyl-2,4-hexadiene (115) represents such a process leading to two regioisomeric oxetanes 116 and 117 where the substrate configuration is retained in 117 [75]. 

Substrate configuration Amide Optical purity of amide (% ee)6 Solvent Optical purity of product (% ee)6... 

Substrate configuration — Terminology used in - photovoltaic devices to designate the device architecture in which the light enters the device through the top face of the cell, i.e., oppositely to the substrate. 

At a later stage, the concepts of protein dynamics were supplemented by the principle of the dynamic adaptation of the enzyme conformational structure to the substrate configuration in consecutive reactions to the enzyme. Such an adaptation promotes both the first step of precise orientation and the subsequent chemical steps, without allowing cleavage of the contacts needed for the chemical mechanism (Likhtenshtein, 1976, 1988a). 

Here, we describe the bio-application of the SERS techniques focused on immunoassay and imaging. It covers the developments in nanostructures for substrates, configurations of measurements, imaging methods, and bio-conjugation technologies. 

Figure 18. Idealized schematic illustration of the tip geometry and the tip-substrate configuration used. From F. F. Fan and A. J. Bard, Science 267 871 (1995) [44].

Generally, stereochemistry of the hydrogenated product is a consequence of the substrate configuration either in the first adsorption step or in the second hydrogen transfer step . Steric considerations may be outweighed by the presence within the molecule of other functionality or a basic atom, which can coordinate to the metal. The side at which the substrate adsorbed is thus determined by an anchor effect, which controls the stereochemical outcome of the reaction. Keto-acid 1 is hydrogenated to hydroxy-acid 2, where the two oxygenated functions are trans ... 

Dihydropyran rearrangements [ 1,4 rearrangements] are known to proceed through a boatlike transition state due to the short tethered chain (see p 3337). If a stereogenic center is attached to the new bond, the product stereochemistry is only governed by the substrate configuration, as shown by the synthesis of the precursor 8 of tetracyclic diterpene ( )-aphidicolin613,614. 

Using a 20-cycle spiral microchannel hot embossed into a polycarbonate (PC) substrate configured for performing CFPCR [89], the PCR cycle time was reduced... 

Present disagreement concerning the reality of reconstructive adsorption at room temperature, as exemplified in Fig. 25, makes it important carefully to consider reconstruction in the light of all the information we now have. In a previous review (70) this author tried to stress the notion that we should discard the assumption that the substrate configuration is effectively unchanged during adsorption. If we do this we can see an underlying unity in observations as apparently diverse as... 

X Medium Substrate configuration Enzyme Steric course at Cp... 

The deposition of thin films of Alq3 was carried out using the horizontal reactor described in Section 2.1. The deposition profiles of organic thin films obtained using OVPD were compared with those prepared by VTE. The VTE source-to-substrate distance was approximately 30 cm and the deposition base pressure was maintained at 10 torr. The mask and substrate configuration is shown in Figure 2.16. 

TERS and theory TERS also provides excellent stimulation and a playground for theoretical studies on enhanced optical processes. The tip-substrate configuration can be considered as a unique photonic system with tunable optical resonances that provides huge near-field enhancements for species located in the tip-substrate cavity. A suitable theoretical description of such a photonic system is, even today, a great challenge, although the general features of such a system are well understood. 

Figure 1.2 Comparison of superstrate and substrate solar cell configurations, (a) Superstrate configuration used for CdSjCdTe solar cells, (b) Substrate configuration commonly used for CIGS solar cells.

Three pathways for the ruthenium-catalyzed hydrogenations of ketones, aldehydes, and a,(3-unsaturated aldehydes with several catalyst systems were studied the direct insertion, the migratory insertion, and the concerted hydrogen transfer highlighting the catalyst/substrate configurations that lead to stereoselective differentiation. The contribution of computational chemistry were essential to differentiate these mechanisms of ruthenium-catalyzed reactions and to rationalize the experimentally observed stereochemical outcome. 

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