Monomolecular

If the surface tension of a liquid is lowered by the addition of a solute, then, by the Gibbs equation, the solute must be adsorbed at the interface. This adsorption may amount to enough to correspond to a monomolecular layer of solute on the surface. For example, the limiting value of in Fig. Ill-12 gives an area per molecule of 52.0 A, which is about that expected for a close-packed... 

It is this potential difference that is discussed in Chapter IV in connection with monomolecular films. Since it is developed in the space between the phases, none of the uncertainties of phase boundary potentials is involved. 

Classic examples are the spontaneous emission of light or spontaneous radioactive decay. In chemistry, an important class of monomolecular reactions is the predissociation of metastable (excited) species. An example is the fonnation of oxygen atoms in the upper atmosphere by predissociation of electronically excited O2 molecules [12, 13 and 14] ... 

Excited O2 molecules are fomied by UV light absorption. Monomolecular reactions (e.g., c = [Oi]) show a first-order rate law ... 

While monomolecular collision-free predissociation excludes the preparation process from explicit consideration, themial imimolecular reactions involve collisional excitation as part of the unimolecular mechanism. The simple mechanism for a themial chemical reaction may be fomially decomposed into tliree (possibly reversible) steps (with rovibronically excited (CH NC) ) ... 

Experimentally, one finds the same first-order rate law as for monomolecular reactions, but with an effective rate constant /rthat now depends on [M],... 

For strictly monomolecular processes the general theory would now proceed by analysing the time-dependent... 

Meot-Ner M 1984 Ionic hydrogen bond and ion solvation 2. Solvation of onium ions by 1-7 water molecules. Relations between monomolecular, specific and bulk hydration J. Am. Chem. Soc. 106 1265-72... 

Blodgett K B 1935 Films built by depositing successive monomolecular layers on a solid surface J. Am. Chem. See. 57 1007-22... 

Barraud A, Rosilio C and Ruaudel-Teixier A 1980 Polymerized monomolecular layers a new class of ultrathin resins for microlithography Thin Soiid Fiims 68 91-8... 

However, all the receptors hitherto discussed are monomolecular species which possess a monomolecular cavity, pocket, cleft, groove or combination of it including the recognition sites to yield a molecular receptor—substrate complex. They can be assembled and preserved ia solution although there are dependences (see below). By way of contrast, molecular recognition demonstrated ia the foUowiag comes from multimolecular assembly and organization of a nonsolution phase such as polymer materials and crystals. 

Fig. 2. Classification/nomenclature of host—guest type inclusion compounds, definitions and relations (/) coordinative interaction, (2) lattice barrier interaction, (J) monomolecular shielding interaction (I) coordination-type inclusion compound (inclusion complex), (II) lattice-type inclusion compound (multimolecular/extramolecular inclusion compound, clathrate), (III) cavitate-type inclusion compound (monomolecular/intramolecular inclusion...

The amount of collector used is necessarily very small because surface coverages of a monomolecular layer or less are required to impart sufficient hydrophobicity to the mineral. The usages typically range from 1—100 g of collector per ton of ore treated for sulfide flotation (typically 0.2—10% value metal content ia the ore) and 100—1000 g/1 for nonsulfide flotation (1—20% value mineral content) (10). 

Paraffin wax additives are effective in overcoming surface inhibition by forming a monomolecular wax layer at the curing surface. Although effective in excluding oxygen, this waxy layer must be removed for subsequent lamination or bonding processes (see Waxes). 

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