Absorption and photoionization cross sections for H2O and D2O in the vacuum ultraviolet

The total absorption, photoionization and neutral product cross sections for H2O and D2O have been determined over the wavelength range 580 to 1050 A. The helium continuum was used as a background with a bandwidth of approximately 0.5 A. Previously observed Rydberg series converging to the (000) level of the ionic ground state have been extended and utilized to obtain ionization thresholds of H2O (982.47 ± 0.5 A, 12.619 ± 0.006 eV) and D2O (981.16 ± 0.5 A, 12.636 ± 0.006 eV). At wavelengths shorter than 1000 A, the total cross section curves for H2O and D2O exhibit a number of previously unreported bands superimposed on broad continua which have peaks at approximately 720 and 925 A. These bands are most likely due to progressions belonging to Rydberg states converging to the first and second excited states of the molecular ion. There is evidence from photographic spectra of H2O16 and H2O18 that the Rydberg states converging to the first excited state of the ion (A2A1) have an effectively linear conformation.

[1]  D. W. Turner,et al.  High resolution molecular photoelectron spectroscopy II. Water and deuterium oxide , 1968, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[2]  J. Johns.  ON THE ABSORPTION SPECTRUM OF H2O AND D2O IN THE VACUUM ULTRAVIOLET , 1963 .

[3]  J. C. Larrabee,et al.  Absorption Coefficients of Xenon and Argon in the 600–1025 Å Wavelength Regions , 1963 .

[4]  H. Rosenstock,et al.  Mass Spectrometric Study of Photoionization V. Water and Ammonia. , 1966, Journal of research of the National Bureau of Standards. Section A, Physics and chemistry.

[5]  S. Bell.  The spectra of H2O and D2O in the vacuum ultraviolet , 1965 .

[6]  G. R. Cook,et al.  On the Continuous Absorption, Photoionization, and Fluorescence of H2O, NH3, CH4, C2H2, C2H4, and C2 , 1964 .

[7]  K. Watanabe,et al.  Absorption Coefficients of Water Vapor in the Vacuum Ultraviolet , 1953 .

[8]  G. Herzberg.  Infrared and raman spectra , 1964 .

[9]  A. S. Jursa,et al.  Absorption and Photoionization Cross Sections of H2O and H2S , 1964 .

[10]  R. Huffman,et al.  Photoionization Study of Diatomic‐Ion Formation in Argon, Krypton, and Xenon , 1966 .

[11]  D. A. Ramsay,et al.  The electronic absorption spectra of NH2 and ND2 , 1959, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[12]  E. N. Lassettre,et al.  HIGH-RESOLUTION STUDY OF ELECTRON-IMPACT SPECTRA AT KINETIC ENERGIES BETWEEN 33 AND 100 eV AND SCATTERING ANGLES TO 16--. , 1968 .

[13]  Edward Teller,et al.  Electronic Spectra of Polyatomic Molecules , 1941 .

[14]  K. Beyer,et al.  Photodissoziationen zu elektronisch angeregten Bruchstücken von H2, H2O und NH3 im extremen Vakuum-UV. II , 1967 .

[15]  Herrick L. Johnston,et al.  The Absorption Spectra of Methane, Carbon Dioxide, Water Vapor, and Ethylene in the Vacuum Ultraviolet , 1950 .

[16]  J. C. Larrabee,et al.  Rare Gas Continuum Light Sources for Photoelectric Scanning in the Vacuum Ultraviolet , 1965 .

[17]  H. Henning.  Die Absorptionsspektren von Kohlendioxyd, Kohlenmonoxyd und Wasserdampf im Gebiet von 600-900 ÅE , 1932 .

[18]  J. C. Larrabee,et al.  Absorption Coefficients of Nitrogen in the 1000–580 Å Wavelength Region , 1963 .

[19]  Stanley S. Ballard,et al.  Techniques of Vacuum Ultraviolet Spectroscopy , 1967 .

[20]  J. Rabalais,et al.  Comments on the high resolution photoelectron spectrum of H2O and D2O , 1971 .

[21]  W. C. Walker,et al.  Preliminary Results on Photoelectric Yields of Pt and Ta and on Photoionization in O2 and N2 in the Vacuum Ultraviolet , 1953 .

[22]  R. Platzman.  Some Remarks on the Nature of Ionization, Ionization Yields, and Isotope Effects in the Ionization of Molecules by Various Agencies , 1963 .

[23]  G. Rathenau.  Untersuchung am Absorptionsspektrum von Wasserdampf und Kohlendioxyd im Gebiet unter 2000 Å , 1934 .

[24]  B. Brehm.  Massenspektrometrische Untersuchung der Photoionisation von Molekülen , 1966 .

[25]  W. Price.  The Far Ultraviolet Absorption Spectra and Ionization Potentials of H2O and H2S , 1936 .

[26]  W. C. Walker,et al.  Photoionization Efficiencies and Cross Sections in O 2 , N 2 , CO 2 , A, H 2 O, H 2 , and CH 4 , 1955 .

[27]  A. Nicholson.  Photoionization‐Efficiency Curves. II. False and Genuine Structure , 1965 .

[28]  J. Berkowitz,et al.  Interpretation of Photoionization Threshold Behavior , 1971 .

[29]  R. Dixon.  The Renner effect in nearly linear molecule, with application to NH2 , 1965 .

[30]  R. Hudson.  CRITICAL REVIEW OF ULTRAVIOLET PHOTOABSORPTION CROSS SECTIONS FOR MOLECULES OF ASTROPHYSICAL AND AERONOMIC INTEREST. , 1971 .

[31]  J. C. Person.  Isotope effects on molecular ionization yields. An extension of the Platzman model. , 1972, Radiation research.