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Schumann-Runge band system

The effects of various added gases on the rate of formation of ozone in a flow system have been studied at 1849 A. with light from a mercury-rare gas low pressure discharge (92). In a 30-mm. diameter cylindrical quartz reaction vessel at a flow rate of 2.0 l./min. at 1-atm. total pressure and 0.25-atm. oxygen pressure, the relative rates of ozone formation were  [Pg.49]

The results are explicable on the basis of primary process (process 5) followed by predissociation to two P atoms and the subsequent reactions (7) and (8). The effects of the foreign gases are thus attributable to their efficiencies as third bodies in reaction (7) in which the expected and ob- [Pg.49]

The photochemical evidence for predissociation obtained in this work and in other studies has been discussed by Volman (94), and will be referred to in later sections. The evidence thus far obtained strongly reinforces the suggestion of Flory (28) that predissociation is possible following absorption in the discrete portion of the Schumann-Runge system. [Pg.50]

Still another interpretation is that of Vanderslice et al. (86) based on potential energy curves derived from approximate quantum-mechanical calculation. Using the crossing point at v = 12 given by Wilkinson and [Pg.50]

Wilkinson and Mulliken (105) have pointed out that a direct transition from 32ff to 3IIU is allowed, and have obtained evidence for a weak continuum attributable to 3nu - 32s. They suggested that this may be more important in the decomposition of oxygen above 1750 A. than predissociation of 32u. If this were the case, the quantum yield of ozone formation would have to be quite small at 1849 A. since most of the light would still be absorbed in the transition 32 32 . Although quan- [Pg.51]


B. Atomspheric photochemistry. The photodissociation of oxygen in sunlight is the major photochemical process occurring in earth s atmosphere. The first intense allowed transition in O., is B - X 32 which occurs at 202.6 nm and is called the Schumann-Runge band system (Section 2.8). It merges intoa continuum beyond 175.9 nm and correlates with one oxygen atom 0(23P) in the ground state and one in the excited state O (2 D)... [Pg.223]

Another important spectral range, between 200 and 175 nm, is related to the 02 Schumann-Runge band system which includes 18 bands, (2-0) to (19-0) subject to the predissociation processes, particularly in the mesosphere. [Pg.64]

Fig. 2. Absorption spectrum of oxygen in the Schumann-Runge band system. The absorption coefficient, k, is defined by the equation I = la exp ( — kx), where h and I are the incident and transmitted light intensities and x is the layer thickness of the absorbing gas reduced to STP. This figure is taken from ref. (101) with the permission of The Journal of Chemical Physics. Fig. 2. Absorption spectrum of oxygen in the Schumann-Runge band system. The absorption coefficient, k, is defined by the equation I = la exp ( — kx), where h and I are the incident and transmitted light intensities and x is the layer thickness of the absorbing gas reduced to STP. This figure is taken from ref. (101) with the permission of The Journal of Chemical Physics.
The most recent studies have been carried out below the convergence limit of the Schumann-Runge band system at 1720 A. (76) and above the convergence limit at 1849 A. (95). Earlier studies in both regions (75) have been critically evaluated, (76) and it was concluded that the analytical procedures used were incorrect. The results obtained by Vol-man above the convergence limit are not substantially different from those reported by Smith and Napravnik below the convergence limit. [Pg.73]

From Ossenbriiggen s work, we know very well the structure of the Schumann-Runge band system of O2, a S —> transition, according to... [Pg.7]

Hudson, R. D., V. L. Carter, and E. L. Breig (1969). Predissociation in the Schumann-Runge band system of 02 Laboratory measurements and atmospheric effects. J. Geophys. Res. 74, 4079-4086. [Pg.668]

Laux, C. O. Kruger, C. H. (1992). Arrays of radiative transition ptrobabihties for the N2 first and second positive, no beta and gamma, N2+ first negative, and O2 Schumann-Runge band systems.. Quant. Spectrosc. Radiant. Transfer, Vol. 48, p>p. 9-... [Pg.249]

The Schumann-Runge bands converge to the limit at 1750 A corresponding to the production of Of3/3) + Of1/)). The integrated absorption coefficients of the Schumann-Runge system from (0,0) to (20,0) have been... [Pg.172]

The determination of the O2 photodissociation frequency in the Schumann-Runge bands is obtained from a computation including the complex rotational structure of the band system. A major difficulty in the calculation of Schumann-Runge band photolysis in the middle atmosphere, in addition to requirements for high spectral resolution, arises from the temperature dependence of absorption cross sections. Polynomial expressions have been derived to reproduce the temperature variation provided by the line-by-line calculations (Minschwaner et al., 1992) this kind of approach, however, is generally not feasible to be implemented in detailed middle atmosphere models, but can be used to develop more efficient broad-band parameterizations (see Section 4.7.3). [Pg.222]

The calculation of the photolysis rate at all atmospheric levels requires detailed knowledge of the solar spectrum. The primary attenuation of the solar flux in the 5 (0-0) band is due to the (5-0) Schumann-Runge band of O2 the attenuation in the 6 (1-0) band is due to the (9-0) and (10-0) bands of O2. Thus, the determination of Jno requires consideration of the ensemble of rotational lines of each NO and O2 band system. Further, the effect of temperature is important in the intensities of both the NO and O2 bands. The vertical temperature structure must therefore be considered for aeronomic studies. The attenuation of the 5 (1-0) band is more rapid than that of the 6 (0-0) band thus the photolysis rate of NO in the stratosphere and lower mesosphere depends... [Pg.235]

The X3 -—> B3X- transition is allowed and as seen in Figs. 4.2 and 4.3 results in an absorption in the 130-to 200-nrn region known as the Schumann-Runge system. The banded structure from about 175 to 200 nm corresponds to transitions from v" = 0 as well as v" = 1 (i.e., hot bands) of the ground X3S state to different vibrational levels of the upper state. [Pg.86]

FIGURE 4-1 Potential energy curves for ground and first four excited states of 02. S-R = Schumann-Runge system, H = Herzberg continuum, A-A = atmospheric bands (adapted from Gay-don, 1968). [Pg.87]

Either of these processes, however, appears to be unlikely, and the first has been rejected by Benson (13). Although radiation from the 32u state is possible, it is precisely the vibrationally excited states of 32 which are known not to radiate. Emission bands in the Schumann-Runge system for v > 2 have not been found (21,94,105), and the evidence is now strong that predissociation from v 3 accounts for the absence of these emission bands. Therefore, it is most probable that reac-... [Pg.58]

Very weak absorption bands in the region 2500 to 3000 A correspond to the forbidden transition /1,ZU+-X 3Z9" (see selection rules 1-10.2). The band system is called the Herzberg 1 band. Second absorption bands in the region 1750 to 2000 A correspond to the B3Z -X3 transition and are called the Schumann-Rungc system. The region 1300 to 1750 A is continuous and is called the Schumann-Runge continuum. Below 1300 A numerous Rydberg transitions have been observed [Yoshino and Tanaka (1066)]. [Pg.172]

Figure 4-44- Detailed structure of the (5-0) band of the Schumann-Runge system of 62 in the spectral range of the 5 (0-0) band of nitric oxide. From Cieslik and Nicolet (1973). Figure 4-44- Detailed structure of the (5-0) band of the Schumann-Runge system of 62 in the spectral range of the 5 (0-0) band of nitric oxide. From Cieslik and Nicolet (1973).
Emission bands of the Schumann-Runge system have also been observed. These are due to transitions from various vibrational levels of the Si state to various vibrational levels of the S state the highest vibrational level of the S state thus detected is at a height 27 840 cm above the ground vibrational state. [Pg.127]


See other pages where Schumann-Runge band system is mentioned: [Pg.47]    [Pg.49]    [Pg.60]    [Pg.28]    [Pg.305]    [Pg.223]    [Pg.71]    [Pg.73]    [Pg.74]    [Pg.47]    [Pg.49]    [Pg.60]    [Pg.28]    [Pg.305]    [Pg.223]    [Pg.71]    [Pg.73]    [Pg.74]    [Pg.3]    [Pg.230]    [Pg.157]    [Pg.64]    [Pg.259]    [Pg.172]    [Pg.51]    [Pg.167]    [Pg.1]    [Pg.5]    [Pg.151]    [Pg.293]    [Pg.301]    [Pg.220]    [Pg.220]    [Pg.236]    [Pg.614]    [Pg.127]    [Pg.219]   
See also in sourсe #XX -- [ Pg.2 , Pg.28 ]




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Band system

Runge

Rungs

Schumann

Schumann-Runge

Schumann-Runge bands

Schumann-Runge system

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