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Observation of the Δv = 1 sequence of OH produced in the H + O3 reaction
RESEARCH TABLE 1. LIST
100.5
NOTES
OF ROCKET
RADIOMETERS
No.
Wavelengths 01)
Resolution (~1)
1 2 3
2.34 2.55 2.70 2.70 2.932 3.300 3.900 4.307 4.700
+@02 ho.02 k-o.02 *0.10 j+o25 &CO76 *0.086 I-to.04 10.105
4
5 6 7 8 9
The last set of data was obtained from an instrumented rocket which was launched in October 1964 at 1823 GMT from Wallops Island, Virginia. The list of radiometers and their spectral characteristics is given in Table 1. Of the many scenes observed, a number of scans at an altitude of 100 km permitted the accumulation of data from ocean, beach and deciduous tree areas. The observed spectral radiances are shown in Fig. 1. Gross differences between the rocket and aircraft data can readily be explained by the difference in observational altitudes, particularly at the longer wavelengths. The specific characteristics that need clarification are the following: (1) the decrease at about 3.56 ,U for orange trees, and (2) the relative magnitudes for beach, ocean terrain and trees. In the complete paper, a comparative analysis of deduced spectral reflectances with other data will be made to establish whether the differences are a result of any measurement errors. R. ZIRKIND Dept. of Aerospace Engineering and Applied Mechanics Polytechnic Institute of Brooklyn Route 110, Farmingdale, New York REFERENCES 1. R. ZIRKIND,Planet. Space Sci. (to be published). 2. 0. AVASTE,Akad. Nauk. Est. SSR 4, 27 (1963).
Planet. Space Sci. 1965. Vol. 13, pp. 1005 to 1008. Pergamon Press Ltd.
OBSERVATION
Printed in Northern Ireland
OF THE Au = 1 SEQUENCE OF OH PRODUCED IN THE H + 0, REACTION* (Received 11 June 1965)
The reaction H + 0, - OH? + 0, is likely to be the primary mechanism for production of excited hydroxyl radicals which result in the Meinel emission bands of the night airglow. c1-a) Previous studies of this reaction in the laboratory have not observed the fundamental band (Au = 1) which lies beyond 2.5 p.(*-” The importance of obtaining data simultaneously on the fundamental and overtone sequences has been demonstrated by Ferguson and Parkinson .(8) These authors point out that without the AU = 1 data any number of functions will represent the variation of dipole moment with internuclear distance calculated from laboratory or night airglow observations of higher sequences .(5.E.81This communication presents the first observation of the AU = 1 sequence from the H + 0, reaction. The H + 0, reaction was studied using a typical steady-state flow system in which the total pressure was 4 torr. A modulated 100 W 2450-M/set microwave discharge was the source of hydrogen atoms. Ozone was synthesized from pure O2 in a high-voltage discharge, adsorbed and stored on silica gel at -78”C, and eluted at -40°C with helium into the reaction cell. This technique, first used by F. Del Greco,llo) has almost eliminated the well-known hazards of handling ozone. Because of the relatively weak source, the emission spectra were observed with an interferometer spectrometer. UU*) The instrument was a typical Michelson design with 2-cm dia. end mirrors. A cooled lead sulphide detector (77°K) was used in obtaining the spectra from 1.4 to 4 1~. The interferogram was digitized every 0.273 ,u by using the 5461 A line of Hg as the fringe monitor. Since the instrument was not 6
FIc;,
1.
off
12-l w---1
EMISSION SPEC?RA
13-210 -
AV=l
FROM
f+
i-
0% REAmION.
DETECTOR
at 77-K
OF OBSERVBD VIBRATiONAL
Cdl
Q BRANCHES
FRECXJEkKY
Pb5
TRANSKTIONS ARE INDICATED.
AL!=2
RESEARCH
1007
NOTES
IOOr
FREQUENCY
(cm- )
FIG. 2. OH EMISSION SPECTRA FROM SAME SYSTEM OBTAINED USING A LONG-PASS FILTER TO INCREASE LONG WAVELENGTHINFORMATION CONTENTININTERFEROGRAM. RESOL~TIONHEREIS ONLY HALF THAT OF FIG. 1 DUE TO DECREASED SIGNAL-TO-NOISERATIO. DETECTOR RESPONSE DETERMINESLOW FREQUENCY CUTOFF.
perfectly compensated over this wide spectral range, the interferogram was asymmetric and therefore, the magnitudes of the spectral elements were determined by taking the square root of the sum of the squares of the sine and cosine transforms. Triangular apodization was used to reduce the side lobes of the scanning function and an IBM 7090 computer performed the Fourier transformation. The OH emission spectrum, which contains most of the Au = 1 and Au = 2 sequences, is shown corrected for the instrument response in Fig. 1. The maximum path difference was only 1 mm, which is not sufficient to resolve the Av = 1 sequence well enough to obtain the integrated intensities of the various vibrational transitions. For example, the Q branches of the 3-2 and 4-3 transitions are resolved only as shoulders in Fig. 1. However, the resolution is sufficient to assign almost all of the observed structure to OH. The Au = 2 sequence was larger by a factor of about 10 before removing the instrument response; consequently, the identification in this region was also unambiguous. It is of interest that under these conditions there is no apparent intensity structure in the spectra at 2.9 and 3.3 ,U as observed in the airglow.u5) The short wavelength limit was imposed by the modulation efficiency of the beam splitter. Figure 2 is the spectrum (uncorrected for instrument response) obtained with a long pass filter to get the higher vibrational transitions with better definition. The 7-6 and 6-5 Q branches are identified. Acknowledgement-The
aid of Michael L. Forman in computer programming
is gratefully acknowledged. A. T. STAIR, JR.
Air Force Cambridge Research Laboratories (O.A.R.) L. G. Hanscom Field, Bedford, Massachusetts Concord Radiance Laboratory of Utah State Davis Road, Bedford, Massachusetts
University
J. P. KENNEALY S. P. STEWART
* The work reported herein has been supported by the Air Force Cambridge Research Laboratories, Office of Aerospace Research, Bedford, Massachusetts under contract AF19(628)-251.
REFERENCES 1. A. B. MEINEL, Astrophys. J. 111, 555 (1950); 112, 120 (1950). 2. D. R. BATES and M. NICOLET, J. Geophys. Res. 55, 301 (1950). 3. G. HERZBERG, J. Roy. Astron. Sot. Canada, 45, 100 (1951). 4. J. D. MCKINLEY.D.GARVIN and M.J.BouDART.J. Chem.Phvs.23,784 (1955). 5. D. GARVIN,H.P:BROIDA,~~~ H.J. KOSTICOWSKI; J. Chem.Ph>s. 32; 880(1960). 6. D. GARVIN, J. Am. Chem. Sot. 81, 3173 (1959). 7. L. DELBOUILLE,G. ROLAND and H. A. GEBBIE, The AstronomicaZJ. 69, 334(1964). 8. A. F. FERGUSON and D. PARKINSON, Planet. Space Sci. 11, 149 (1963).
100s
RESFARCH
NOTES
9. V. I. KRMWVSKY, N. N. SHEFOVand V. I. YARIN, J. Atmos. Terr. Phys. 21,46 (1961). 10. F. KAUFMAN, Private communication. 11. P. JACQUINOT, J. Phys. Radium, 19,223 (1958). 12. J. COGS, Revue SOpique, 40,4.5,116,1?1 and 231 (1961). 13. E. A. LYTLEand J. HAMPSON, Nature, Land. 202,76 (1964).
Planet. SpaceSci.1965,
Vol.
13,pp. 100sto 1009.
CORPUSCULAR
Pergamm
Press Ltd.
Printed
BOMBARDMENT
in Northern
Xreland
AND Na+ RADIATION
(Received 22 Jtine 1965) The axsrgy flux of a beam of fast electrons absorbed by the atmosphere can be derived from the resulting intensity of the first negative system of molecuIar nitrogen. (I2 The procedure is based upon the observation that the variation with impact energy E of the cross section for the production of the upper state of the first negative system by electron impact with N,‘B*8t e + N,(XIC,+) -+ e -i- N,+(BaX%,+)+ e
(1)
is very similar to that of the total ionization cross section’4-8’ e + N,(XG,+}
-+ e + CN*,f + e
(2)
and the further observation that the mean energy expended in the production of an ion pair by a beam of discrepancy between fast electrons absorbed in nitrogen is a constant of about 35 eV (@).There is a ~~i~~nt the efbciency derived from the cross section measurements of Stew~t~~l and of Hayakawa and Nishimura~a~ and the ethciency measured directly by Hartman and Hoerlin’**” (cf. Dalgarnoun). New more precise m~~rnents of the cross sections for (1) have been presented resently by Latimer and McConkey W) which largely remove the discrepancy, The ratio of the cross section for the production of an ion pair@-@ to the cross section for the production of a 3914 8, photon’12) is shown in Fig. 1 for electron impact energies uu to 300eV. The ratio is very nearlv constant and we adopt a value of 17 for it. The ef&iency wi?h w&h kinetic energy is transfor&ted inio 3914 A photon energy when an electron beam is absorbed in nitrogen is accordinelv 5.0 x 1W and for an electron beam absorbed in air it is 4-O x IO+. The value for air Measured by H&&ran and HoerlW”) is 3.3 x 1W. A mean value of 3.7 X lo-% appears to be an acceptable compromise. It is within the experiments error quoted by McConkey and Latimeroa). The value of the energy conversion coefficient appropriate to the upper atmosphere depends upon the
18
1
1
loo Electron FIG.
1.
RELATIVE
,
300
200
IOMZATION
energy, CROSS
eV
SECTIONS
IN
NITRWEN.
100.5
NOTES
OF ROCKET
RADIOMETERS
No.
Wavelengths 01)
Resolution (~1)
1 2 3
2.34 2.55 2.70 2.70 2.932 3.300 3.900 4.307 4.700
+@02 ho.02 k-o.02 *0.10 j+o25 &CO76 *0.086 I-to.04 10.105
4
5 6 7 8 9
The last set of data was obtained from an instrumented rocket which was launched in October 1964 at 1823 GMT from Wallops Island, Virginia. The list of radiometers and their spectral characteristics is given in Table 1. Of the many scenes observed, a number of scans at an altitude of 100 km permitted the accumulation of data from ocean, beach and deciduous tree areas. The observed spectral radiances are shown in Fig. 1. Gross differences between the rocket and aircraft data can readily be explained by the difference in observational altitudes, particularly at the longer wavelengths. The specific characteristics that need clarification are the following: (1) the decrease at about 3.56 ,U for orange trees, and (2) the relative magnitudes for beach, ocean terrain and trees. In the complete paper, a comparative analysis of deduced spectral reflectances with other data will be made to establish whether the differences are a result of any measurement errors. R. ZIRKIND Dept. of Aerospace Engineering and Applied Mechanics Polytechnic Institute of Brooklyn Route 110, Farmingdale, New York REFERENCES 1. R. ZIRKIND,Planet. Space Sci. (to be published). 2. 0. AVASTE,Akad. Nauk. Est. SSR 4, 27 (1963).
Planet. Space Sci. 1965. Vol. 13, pp. 1005 to 1008. Pergamon Press Ltd.
OBSERVATION
Printed in Northern Ireland
OF THE Au = 1 SEQUENCE OF OH PRODUCED IN THE H + 0, REACTION* (Received 11 June 1965)
The reaction H + 0, - OH? + 0, is likely to be the primary mechanism for production of excited hydroxyl radicals which result in the Meinel emission bands of the night airglow. c1-a) Previous studies of this reaction in the laboratory have not observed the fundamental band (Au = 1) which lies beyond 2.5 p.(*-” The importance of obtaining data simultaneously on the fundamental and overtone sequences has been demonstrated by Ferguson and Parkinson .(8) These authors point out that without the AU = 1 data any number of functions will represent the variation of dipole moment with internuclear distance calculated from laboratory or night airglow observations of higher sequences .(5.E.81This communication presents the first observation of the AU = 1 sequence from the H + 0, reaction. The H + 0, reaction was studied using a typical steady-state flow system in which the total pressure was 4 torr. A modulated 100 W 2450-M/set microwave discharge was the source of hydrogen atoms. Ozone was synthesized from pure O2 in a high-voltage discharge, adsorbed and stored on silica gel at -78”C, and eluted at -40°C with helium into the reaction cell. This technique, first used by F. Del Greco,llo) has almost eliminated the well-known hazards of handling ozone. Because of the relatively weak source, the emission spectra were observed with an interferometer spectrometer. UU*) The instrument was a typical Michelson design with 2-cm dia. end mirrors. A cooled lead sulphide detector (77°K) was used in obtaining the spectra from 1.4 to 4 1~. The interferogram was digitized every 0.273 ,u by using the 5461 A line of Hg as the fringe monitor. Since the instrument was not 6
FIc;,
1.
off
12-l w---1
EMISSION SPEC?RA
13-210 -
AV=l
FROM
f+
i-
0% REAmION.
DETECTOR
at 77-K
OF OBSERVBD VIBRATiONAL
Cdl
Q BRANCHES
FRECXJEkKY
Pb5
TRANSKTIONS ARE INDICATED.
AL!=2
RESEARCH
1007
NOTES
IOOr
FREQUENCY
(cm- )
FIG. 2. OH EMISSION SPECTRA FROM SAME SYSTEM OBTAINED USING A LONG-PASS FILTER TO INCREASE LONG WAVELENGTHINFORMATION CONTENTININTERFEROGRAM. RESOL~TIONHEREIS ONLY HALF THAT OF FIG. 1 DUE TO DECREASED SIGNAL-TO-NOISERATIO. DETECTOR RESPONSE DETERMINESLOW FREQUENCY CUTOFF.
perfectly compensated over this wide spectral range, the interferogram was asymmetric and therefore, the magnitudes of the spectral elements were determined by taking the square root of the sum of the squares of the sine and cosine transforms. Triangular apodization was used to reduce the side lobes of the scanning function and an IBM 7090 computer performed the Fourier transformation. The OH emission spectrum, which contains most of the Au = 1 and Au = 2 sequences, is shown corrected for the instrument response in Fig. 1. The maximum path difference was only 1 mm, which is not sufficient to resolve the Av = 1 sequence well enough to obtain the integrated intensities of the various vibrational transitions. For example, the Q branches of the 3-2 and 4-3 transitions are resolved only as shoulders in Fig. 1. However, the resolution is sufficient to assign almost all of the observed structure to OH. The Au = 2 sequence was larger by a factor of about 10 before removing the instrument response; consequently, the identification in this region was also unambiguous. It is of interest that under these conditions there is no apparent intensity structure in the spectra at 2.9 and 3.3 ,U as observed in the airglow.u5) The short wavelength limit was imposed by the modulation efficiency of the beam splitter. Figure 2 is the spectrum (uncorrected for instrument response) obtained with a long pass filter to get the higher vibrational transitions with better definition. The 7-6 and 6-5 Q branches are identified. Acknowledgement-The
aid of Michael L. Forman in computer programming
is gratefully acknowledged. A. T. STAIR, JR.
Air Force Cambridge Research Laboratories (O.A.R.) L. G. Hanscom Field, Bedford, Massachusetts Concord Radiance Laboratory of Utah State Davis Road, Bedford, Massachusetts
University
J. P. KENNEALY S. P. STEWART
* The work reported herein has been supported by the Air Force Cambridge Research Laboratories, Office of Aerospace Research, Bedford, Massachusetts under contract AF19(628)-251.
REFERENCES 1. A. B. MEINEL, Astrophys. J. 111, 555 (1950); 112, 120 (1950). 2. D. R. BATES and M. NICOLET, J. Geophys. Res. 55, 301 (1950). 3. G. HERZBERG, J. Roy. Astron. Sot. Canada, 45, 100 (1951). 4. J. D. MCKINLEY.D.GARVIN and M.J.BouDART.J. Chem.Phvs.23,784 (1955). 5. D. GARVIN,H.P:BROIDA,~~~ H.J. KOSTICOWSKI; J. Chem.Ph>s. 32; 880(1960). 6. D. GARVIN, J. Am. Chem. Sot. 81, 3173 (1959). 7. L. DELBOUILLE,G. ROLAND and H. A. GEBBIE, The AstronomicaZJ. 69, 334(1964). 8. A. F. FERGUSON and D. PARKINSON, Planet. Space Sci. 11, 149 (1963).
100s
RESFARCH
NOTES
9. V. I. KRMWVSKY, N. N. SHEFOVand V. I. YARIN, J. Atmos. Terr. Phys. 21,46 (1961). 10. F. KAUFMAN, Private communication. 11. P. JACQUINOT, J. Phys. Radium, 19,223 (1958). 12. J. COGS, Revue SOpique, 40,4.5,116,1?1 and 231 (1961). 13. E. A. LYTLEand J. HAMPSON, Nature, Land. 202,76 (1964).
Planet. SpaceSci.1965,
Vol.
13,pp. 100sto 1009.
CORPUSCULAR
Pergamm
Press Ltd.
Printed
BOMBARDMENT
in Northern
Xreland
AND Na+ RADIATION
(Received 22 Jtine 1965) The axsrgy flux of a beam of fast electrons absorbed by the atmosphere can be derived from the resulting intensity of the first negative system of molecuIar nitrogen. (I2 The procedure is based upon the observation that the variation with impact energy E of the cross section for the production of the upper state of the first negative system by electron impact with N,‘B*8t e + N,(XIC,+) -+ e -i- N,+(BaX%,+)+ e
(1)
is very similar to that of the total ionization cross section’4-8’ e + N,(XG,+}
-+ e + CN*,f + e
(2)
and the further observation that the mean energy expended in the production of an ion pair by a beam of discrepancy between fast electrons absorbed in nitrogen is a constant of about 35 eV (@).There is a ~~i~~nt the efbciency derived from the cross section measurements of Stew~t~~l and of Hayakawa and Nishimura~a~ and the ethciency measured directly by Hartman and Hoerlin’**” (cf. Dalgarnoun). New more precise m~~rnents of the cross sections for (1) have been presented resently by Latimer and McConkey W) which largely remove the discrepancy, The ratio of the cross section for the production of an ion pair@-@ to the cross section for the production of a 3914 8, photon’12) is shown in Fig. 1 for electron impact energies uu to 300eV. The ratio is very nearlv constant and we adopt a value of 17 for it. The ef&iency wi?h w&h kinetic energy is transfor&ted inio 3914 A photon energy when an electron beam is absorbed in nitrogen is accordinelv 5.0 x 1W and for an electron beam absorbed in air it is 4-O x IO+. The value for air Measured by H&&ran and HoerlW”) is 3.3 x 1W. A mean value of 3.7 X lo-% appears to be an acceptable compromise. It is within the experiments error quoted by McConkey and Latimeroa). The value of the energy conversion coefficient appropriate to the upper atmosphere depends upon the
18
1
1
loo Electron FIG.
1.
RELATIVE
,
300
200
IOMZATION
energy, CROSS
eV
SECTIONS
IN
NITRWEN.