Conventions upper/lower states

So far as rule 2 is concerned, since AJ is conventionally taken to refer to J -J", where J is the quantum number of the upper state and J" that of the lower state of the transition, AJ = — 1 has no physical meaning (although it emerges from the quantum mechanics). It is commonly, but incorrectly, thought that AJ = +1 and AJ = — 1 refer to absorption and emission, respectively in fact AJ = +1 applies to both. Transition wavenumbers or frequencies are given by... 

The convention of indicating a transition involving an upper electronic state N and a lower electronic state M by N-M is analogous to that used in rotational and vibrational spectroscopy. 

In spectroscopic convention, the upper energy state is written first followed by the lower energy state between which the transition is taking place. For absorption, the arrow points from left to right, e.g. for the lowest energy transition in benzene at 260 nm, in absorption 1B2u - 1A,t and in emission ih - Mw. Other nomenclatures are given in the Table 3.4. 

Ue in (6.7), the value at the equilibrium geometry of the potential energy for nuclear motion. The convention is to denote quantities of the upper electronic state of a transition by single primes, and quantities of the lower electronic state by double primes. The symbols Te, G, and F are used for the electronic, vibrational, and rotational energies in cm-1 ... 

Sequence of Symbols.—Spectroscopists have agreed, internationally, upon a convention for the description of radiative and absorptive transitions between molecular states. The symbol for the upper state is always written first and the lower state last regardless of whether the process is... 

Conventional chemical wisdom states that metallic elements are more reactive on the lower left side of the periodic table, and nonmetallic elements are more reactive on the upper right side of the periodic table. Electrochemically, this suggests that fluorine and cesium would have the extreme values of F. Fluorine does have a very positive F with respect to the SHE, at 2.87 V. However, lithium has one of the highest F values for a metal, at 3.045 V. (Cesium s is only -2.92 V.) Can you explain this ... 

In the case of H2O it is easy to see from the form of the normal modes, shown in Figure 4.15, that all the vibrations Vj, V2 and V3 involve a change of dipole moment and are infrared active, that is w=l-0 transitions in each vibration are allowed. The transitions may be labelled Ig, 2q and 3q according to a useful, but not universal, convention for polyatomic molecules in which N, refers to a transition with lower and upper state vibrational quantum numbers v" and v, respectively, in vibration N. 

Note that in all these equations we have used the convention that the upper sign of the + and + symbols refers to upward particle movement (active state) and the lower sign to downward particle movement (passive state). The symbols D Dc, Ds, and Dy are called distribution factors, corresponding to conical, cylindrical, trapezoidal, and rectangular tube sections, respectively. 

Here we have used the conventional notation of representing the energies in the bands by the symmetry of the wave function. We arc not concerned with the symmetry here, but specific labels will help. The designation A indicates k in a [100] direction. Bands indicated by A, are doubly degenerate and in this case arc the upper bands which are made up of /)-likc states. The A, bands arc nondegener-ate and, here, are the lower bands with mixed s and p symmetry. 

The more conventional method for studying the energetics of diffusion in membranes is to perform permeation experiments as a function of equilibrium temperature. Figure 13 illustrates the eflEect of temperature on the apparent diflEusion coeflScient calculated from the water vapor permeation time lag established by steady-state permeation with a 75 to 0% RH gradient across the membrane. The principles of the time lag permeation method are adequately discussed elsewhere (58). The lower curve corresponds to a sample which was not mechanically supported and was observed to deform into a hemispherical shape. This deformation is the combined result of a small pressure diflEerence across the membrane and a decrease in modulus of stratum corneum as the temperature is increased. The upper curve corresponds to a supported sample. Previous to the experiment, both samples had identical thermal histories. Stresses accompanying deformation of the unsupported cor-... 

Throughout we will use the convention that when computing the transition frequency we will take the energy of the upper state minus the energy of the lower. AE = Supper Slower-... 

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