Laboratory CO2 photolysis studies related to planetary atmospheres

The CO(a 3II) state, the upper state of the Cameron bands, was characterized with respect to its average radiative lifetime and its quenching coefficients for a series of simple molecules. The CO2 recombination reaction (O(3P) + CO + M yields CO2 + M) was studied as a function of temperature. For M = CO, the rate constant can be expressed as k = 6.5 x 10/33 exp(-4340 plus or minus 550/RT) cm to the 6th power molec/2 sec/1, whereas the rate for M = CO2, the pertinent species in the planetary atmospheres, is 1.6 times greater. The quantum yield for CO2 photodissociation was measured in the 1200-1500 A region, using atomic line sources. The yield throughout this spectral region was much lower than that measured at 1470 A, the lowest value obtained being 8% at 1304 A

Photodissociation of CO2 and quenching of metastables

Investigations in four different areas were carried out to further our understanding of the chemistry of the atmospheres of Mars and Venus. CO2 photodissociation quantum yields were determined in the 1300-1500 A spectral region by measuring both CO and oxygen atoms. The O(1S) quantum yield was determined for CO2 photodissociation in the 1060-1175 A spectral region. The measurement resolves the differences between two earlier experiments, and demonstrates that the O(1S) yield is unity throughout most of the measured region. The pathways for the quenching of O(1S) by N2O, CO2, H2O and NO were investigated and the source of the Venus nightglow, detected by Venera 9 and 10, was investigated. What appears to be a new O2 band system, was detected although the identity of the transition is not yet evident

The source of stratospheric NO and N2O

The photodissociation of O3 was investigated as a possible sources of N2O production in the stratosphere. Photolysis was conducted at 1576 A to generate the excited O2 states that react with N2 to form N2O. At this wavelength, there is a quantum yield of two for prompt production of oygen atoms, which is a consequence of the existence of two photodissociative channels giving comparable yields. One of these channels gives O(D1) and O2(b1sigma(+)subg), with a quantum yield of 0.6, whereas the other results in fragmentation of the O3, with production of three ground state oxygen atoms. The O2(b) is generated with vibrational excitation, and there are comparable populations in levels O to 3. These observations are the first to show O2(b) production from any photodissociative process, and were made under conditions in which the kinetics of vibrationally excited O2(b) can be studied. It appears that O3 photodissociation at 1576 A is not a good system for generating the higher electronic states of O2; it is likely that better results will be obtained at 1930 A

Laboratory CO2 photolysis studies related to planetary atmospheres Semiannual report, 15 Jul. 1969 - 15 Jan. 1970

Oxygen and carbon dioxide UV photolysis studied with resonance fluorescence to analyze planetary atmospheric processe

A study of teacher perceptions of the use of student growth measures in teacher evaluation and its effect on school culture

This study explored teacher perceptions of the inclusion of student growth data into the teacher evaluation process and the relationship(s) these perceptions might have on school culture. A positive correlation (p \u3c.001) was found between the inclusion of VAM into the teacher evaluation process and motivation to collaborate. Key findings include participants working in priority designated schools were less likely to collaborate; participants with more knowledge about VAM had more positive perceptions; and participants in nonurban schools or smaller schools had more positive perceptions of VAM. Significant main effects for urban location (p = .001), number of teachers (p = .005), and level of knowledge (p = .05) were found. Participants in priority or urban schools indicated they don’t want to collaborate at a higher level than their counterparts in non-priority or nonurban schools. The inclusion of VAM appears to lead participants into isolation, not necessarily competitive relationships

Laboratory CO2 photolysis studies related to planetary atmospheres Final report, 15 Jul. 1969 - 15 Jul. 1970

Photolysis of CO-2 in UV spectral region applied to models of Martian and Venusian atmosphere

Atmospherically Related Studies of O(D-1) and O2 (b'Sigma(sub g, sup +)

For the third year of the grant, we propose to investigate the (beta)'(Sigma)(sub g, sup +). Our earlier value of 0.77 +/- 0.23, which has been used for a long time, should be updated, and the error limits reduced. Current measurements in J. Barker's group at the University of Michigan have assigned a value closer to 0.9, and we will conduct a new evaluation. The goals of this project are to investigate various aspects of the photochemistry of O('D) and O2(beta)'(Sigma)(sub g, sup +) that are of relevance to the photochemistry and energy balance of the terrestrial atmosphere. Over the last six months, we have obtained new sky spectra data files from the Keck telescope via Don Osterbrock at UC Santa Cruz, and now 120 hours of data have been accumulated. Thus, we have been able to make large signal/noise improvements of the O2(b'(Sigma)(sub g, sup +) - X(sup 3)(Sigma)(Sub g, sup -) Atmospheric Band data that we are collecting

CO2 photodissociation and vibrational excitation in the planetary atmospheres

The principal subjects of investigation were the determination of the CO2 photodissociation quantum yields at the wavelengths from 1200 A to 1500 A, and the efficiency of electronic-to-vibrational energy transfer in the systems 0(1D) + CO, N2, CO2 yields 0(3P) + CO N2, CO2 vibrational energies. Measurements on the photodissociation quantum yield of CO2 in the 1200-1500 A region show that it is wavelength dependent, and for the six atomic line sources used, the quantum yield varied from 0.2 to 0.8. The data appear to fit the interpretation of stable CO2 bound states mixed with repulsive or predissociating states, since the low quantum yields coincide with the maximum structure in the CO2 absorption spectrum. The first reliable measurements were made on the efficiency of electronic-to-vibrational energy transfer in the systems 0(1D)-CO and 0(1D)-N2, using a uv resonance fluorescence technique. The 0(1D)-CO2 interaction was investigated by infrared techniques

Atmospheric Oxygen Photoabsorption

The work conducted on this grant was devoted to various aspects of the photophysics and photochemistry of the oxygen molecule. Predissociation linewidths were measured for several vibrational levels in the O2(B3 Sigma(sub u)(sup -)) state, providing good agreement with other groups working on this important problem. Extensive measurements were made on the loss kinetics of vibrationally excited oxygen, where levels between v = 5 and v = 22 were investigated. Cavity ring-down spectroscopy was used to measure oscillator strengths in the oxygen Herzberg bands. The great sensitivity of this technique made it possible to extend the known absorption bands to the dissociation limit as well as providing many new absorption lines that seem to be associated with new O2 transitions. The literature concerning the Herzberg band strengths was evaluated in light of our new measurements, and we made recommendations for the appropriate Herzberg continuum cross sections to be used in stratospheric chemistry. The transition probabilities for all three Herzberg band systems were re-evaluated, and we are recommending a new set of values