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Integrated circuits --- Ion beam lithography --- Photolithography --- X-ray lithography --- Very large scale integration --- Design and construction --- Congresses --- Congresses --- Congresses --- Congresses

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Catalysis. --- Nuclear magnetic resonance. --- Catalyse --- Résonance magnétique nucléaire --- Catalysis --- Magnetic Resonance Imaging --- Chemical Processes --- Diagnostic Imaging --- Tomography --- Physicochemical Processes --- Diagnostic Techniques and Procedures --- Physicochemical Phenomena --- Chemical Phenomena --- Phenomena and Processes --- Diagnosis --- Analytical, Diagnostic and Therapeutic Techniques and Equipment --- Physical & Theoretical Chemistry --- Chemistry --- Physical Sciences & Mathematics --- 544.47 --- Catalysis. Catalytic reactions --- Magnetic resonance, Nuclear --- NMR (Nuclear magnetic resonance) --- Nuclear spin resonance --- Resonance, Nuclear spin --- Chemistry. --- Analytical chemistry. --- Physical chemistry. --- Analytical Chemistry. --- Physical Chemistry. --- Activation (Chemistry) --- Chemistry, Physical and theoretical --- Surface chemistry --- Magnetic resonance --- Nuclear spin --- Nuclear quadrupole resonance --- Analytical biochemistry. --- Chemistry, Physical organic. --- Chemistry, Physical organic --- Chemistry, Organic --- Analytic biochemistry --- Biochemistry --- Chemistry, Analytic --- RMN en la Industria Química y Agroalimentaria (71101110) --- Bibliografía recomendada --- Bioanalytic chemistry --- Bioanalytical chemistry --- Analytical chemistry --- Chemistry, Theoretical --- Physical chemistry --- Theoretical chemistry --- Analysis, Chemical --- Analytic chemistry --- Chemical analysis --- Magnetic resonance imaging --- Clinical magnetic resonance imaging --- Diagnostic magnetic resonance imaging --- Functional magnetic resonance imaging --- Imaging, Magnetic resonance --- Medical magnetic resonance imaging --- MR imaging --- MRI (Magnetic resonance imaging) --- NMR imaging --- Nuclear magnetic resonance --- Nuclear magnetic resonance imaging --- Cross-sectional imaging --- Diagnostic imaging --- Diagnostic use

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Achemist,facedwiththeproblemofdeterminingthemechanismofachemical reaction, tries to identify a set of reactions that will account for the observed behavior:Ideally,asmallsetofknownreactionsshoulddescribeingreatdetail exactly what takes place at each stage of a chemical transformation. The fact that many reactions proceed in a stepwise fashion can most convincingly be demonstrated if intermediate species can be isolated and shown to proceed to the same products under otherwise identical reaction conditions. An - termediate is the reaction product of each of these steps, except for the last onethatformsthe?nalproduct. Someintermediatesarestablecompoundsin theirownright;someothers,however,aresoreactivethattheirisolationisnot possible. Occasionally, evidence for the existence of short-lived intermediates may be obtained, in particular by spectroscopic observation. The latter may - low a direct observation or an indirect inference from unusual phenomena occurring in the reaction products during in situ investigations of their c- responding chemical reactions. In NMR spectroscopy, for example, transient emissionandenhanced absorptionlinesmaybeobserved, andoneisinclined to believe that there is a universal and unambiguous reason for their appe- ance. Thisisnotnecessarilythecase,however,sincethisseeminglyidentical phenomenon may have a strikingly different origin: During free radical re- tions,aphenomenoncalledchemicallyinduced dynamicnuclear polarization (CIDNP) may give rise to virtually the same effect as occasionally observed duringhomogeneous(andpossiblyevenheterogeneous)hydrogenations:The latter phenomenon, called parahydrogen-induced polarization (PHIP), has a completely different physical basis. It was ?rst noticed twenty years later than CIDNP and occurs if there is an imbalance of the two spin isomers of symmetric molecules such as dihydrogen when hydrogenating unsaturated compoundsusingappropriatecatalysts. Thesetwoeffects,ifnotdifferentiated properly, can cause misinterpretations of reaction mechanisms, as occurred initially when their different origins had not yet been understood approp- ately.

544.47 --- Catalysis. Catalytic reactions