Gas number density

We can connect this energy shift per perturbing atom to an absolute average shift by multiplying by the rare gas number density N and integrating over the volume. If we also replace U(ft,ft,r,R) using Eq. (11.19), Eq. (12.16) becomes... 

Reactions (1) and (2) essentially convert solar radiant energy into thermal energy. The parameters which determine the rate of ozone formation (UV photon flux, atomic and molecular oxygen number density and the total gas number density) are not constant with altitude and so the ozone concentration and hence Tg varies with altitude. The net result is that Tg increases thoughout the stratosphere until a maximum is reached at the stratopause whence Tg begins to decrease again. 

The concentration of Na was changed by varying the Na concentration of solutions used with an aspirating slot burner. This plot indicates that Na can be measured down to 10 ppt relative to the flame gas number density and that the response is linear over the concentration range measured. 

In this expression the second term gives all the information about the interaction between the electron and the particular gas molecule and the third term contains the parameters available to the experimenter i.e., the electron field and the gas number density. Since the number density is proportional to the gas pressure, the experimental quantity of major relevance is the ratio E/p. 

By rearranging Equation (241) and applying the chain rule, we may write for the gas number density... 

If we can write an equation for the chemical potential of a molecule as a function of pair potentials, p = /(p), and find the derivative of the chemical potential with the number density in terms of pair potential energies, we may solve the above integration. Since we know the p2 = P + kT nX2 expression per molecule from Equation (165), where X2 is usually expressed as the mole fraction or volume fraction, we need to relate the chemical potential of pure gas, p, to the molecular pair potentials and also the mole fraction, X2, to the gas number density, p. As the chemical potential, p2, is the total free energy per mole, it includes the interaction energy, p2, as well as enthalpy (kT) and entropy of mixing (kh X2) contributions. 

Electron swarm measurements (Huxley and Crompton, 1974), in which a burst of electrons is observed to drift along an electric field applied to a low-density gas and various transport coefficients, such as the drift velocity, transverse or longitudinal diffusion coefficients, attachment or ionization coeffieients, and so on, are measured as functions of the applied electric field divided by the pressure or the gas number density (i.e., E/p or E/N) collision cross sections, which are related to the transport coefficients through Boltzmann s transport equation (Morgan, 1979 Morgan and Penetrante, 1990), can be extracted by a process of inversion. 

Petrovic et al. (1990) measured the rate coefficients for low-energy electron attachment to BCI3, as functions of E/N, electric field divided by gas number density, in an electric discharge in an N2/BCI3 mixture. 

Differential Mobility-MS for Explosive Threat Detection Differential mobility spectrometry (DMS), also known as FAIMS, is a technique closely related to IMS [191-192]. In this system, the ratio of the electric field strength (E, V/cm) applied to the electrodes to the drift gas number density (N, cm" ) is increased to a level beyond that used in DT-IMS (the most common configuration of IMS systems) so that the mobility of the ion (K) is no longer constant but is dependent on the strength of E/N (Townsend [Td]) [192]. 

For electrostatic fields higher than the low-field limit, the ion velocity distribution depends less strongly on the temperature of the separation and the mean ion energy increases as it traverses the drift region. Consequently, K is no longer constant and depends on the specific ratio of the electrostatic field to the gas number density (E/N) see (26) for a derivation of calculating the low-field limit for a particular analyte). 

If the number density is defined as the gas number density under STP conditions (A =2.687 xioi9cm-3), then... 

Examples of the various types of observed uniform field behavior of the breakdown voltage (Vs)mix of binary gas mixtures with respect to those (Vs)a,b of the individual components A, B as a function of gas composition are shown in Fig. 4. Figure 4a shows the behavior of (Vs)mix for binary mixtures of electronegative gases whose A a(( )) is independent of gas number density N. The (Vs)mix is nearly equal to the sum of the partial-pressure-weighted... 

In Fig. 4c the behavior of curve I is interesting in that for certain gas compositions the (Vs)mix exceeds the Vs of either component. This has been observed for other binary mixtures (e.g., I-C3F6/C-C4F8 I-C3F6/SO2 SO2/SF6 C3F8/SF6 and OCS/SF6) for which the electron-attachment properties of one or both of the constituent gases depend on the total gas pressure and the mixture composition. This is clearly seen by the data in Fig. 4d, which show the variation of (Vs)mix for SF6/I-C3F6 with relative composition and total gas number density. 

The Vs of a gaseous medium is expected, in accordance with Paschen s law, to be a function only of Nds (the product of the gas number density N and the electrode separation ds) thus, for sufficiently high values of N to the right of the Paschen minimum, Vs/Nds = (E/N) ijn should be independent of N. This relationship holds for... 

Since v is inversely proportional to the buffer gas number density N, the mobility K is also inversely proportional to N. Here N (in units of molecules per volume) is used as the relevant quantity to express pressure because N is, in contrast to pressure p, decoupled from the temperature T. Because K depends on N it is practical to convert K into the pressure-independent quantity [Pg.4]

In the above expression, K is the measured ionic mobility, N is the gas number density, is the ion s effective temperature, p is the ion-gas reduced mass term, and Oj(T ) is the averaged ion collision cross section. The effective ion temperature is a composite of the drift gas temperature and the energy the ion gains from the electric field ... 

How, then do Rydberg states evolve as the gas number density N (or the gas density p) increases from a low pressure gas to the condensed... 

Xe) on the gas number density over the entire density range from the low... 

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