Unit path

Specific rotation (Section 7 4) Optical activity of a substance per unit concentration per unit path length... 

As the attenuation of the incident beam per unit path through the solution, the turbidity is larger than the Rayleigh ratio by the factor Ibrr/S, since T is obtained by integrating Rg over a spherical surface. Thus, if Eq. (10.54) is written in terms of Rg rather than r, the proportionality constant H must also be decreased by l6n/3, in which case the constant is represented by the symbol K ... 

Linear Energy Transfer (LET)—A measure of the energy that a charged particle transfers to a material per unit path length. 

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Stopping power or linear energy transfer (LET) is the energy lost per unit path length. Equation 6-2 expresses this relationship. 

Stopping power is the energy lost per unit path length. 

For the individual components, the coefficients sa,x> b,x>. .., z,x can be regarded as absorbances normalised to unity concentration (1 M) and unit path length (1 cm). They have units of M em, absorbances y have no units. For simplicity, we have set the path length 1= 1cm. 

A fundamental unit in spectroscopy (synonymous with molar extinction coefficient) and symbolized by e. It is equal to the absorbanee of light per unit path length and per unit eoncentration. See Absorption Spectroscopy Beer-Lambert Law... 

In this condition, Bethe formulated the stopping power for electron according to the Born approximation. Stopping power is a property of irradiated materials and gives the amount of energy deposited per unit path length, —dU/dx. 

Equation (24) shows that the units of Re are those of r2(isli0). The units of the first factor are length and those of the second length-3. Therefore Re has the units length-1. By Equations (35) and (37), the units of r are the same as Re. Each of these parameters measures the light attenuation per unit path length. 

The photoionization efficiency is defined as the number of ions, produced by one incident photon on unit path length at unit gas pressure. The curves in Figures 3-6 represent spectral efficiency curves. On them the ratio of the measured photocurrent to the number of incident monochromatic photons is plotted as function of the photon energy (in e.v.). At the low pressure used in the mass spectrometer (< 10 3 torr) the efficiency curves are proportional to the photoionization cross-section curves.3... 

A(y) = A(v)/v. Whereas A describes the absorption of spectral intensity or energy, A is proportional to the probability of absorbing a photon per unit path length. We will not make great use of the quantity A, because the spectral density G defined above is more closely related to the squared dipole transition matrix elements, even at low frequency G is the preferred quantity. 

If a medium is considered as an ensemble of individual molecules, the average energy losses of a charged particle on electron retardation per unit path length can be calculated according to the formula... 

The energy losses per unit path length in collisions with impact parameters exceeding some given value b can be presented as... 

Fig. 18. Dependence on electron energy of the VCR photon yield in the spectral range (200-600 nm) per unit path length (1), and of the total number of photons in the spectral range (200-600 nm) emitted along the track (2) in water.

There may be a contrast between the effects of various types of ionization. With a heavy particle such as an alpha particle or a proton the specific ionization is very high, that is, many ions are formed per unit path length. Thus ion-ion, ion-radical, and radical-radical reactions may be very important because concentrations of these intermediates are high. With particles of lower mass, such as photoelectrons, the specific ionization is much lower and the chance of second order effects much less. Thus the effect of specific ionization bears some resemblance to that obtained with rotating sectors and pulse radiolysis. 

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