The gas phase infrared spectra of the hydrated hydronium cluster ions H3O+·(H2O)n(n=1, 2, 3) have been observed from 3550 to 3800 cm^−1. The new spectroscopic method developed for this study is a two color laser scheme consisting of a tunable cw infrared laser with 0.5 cm^−1 resolution used to excite the O–H stretching vibrations and a cw CO2 laser that dissociates the vibrationally excited cluster ion through a multiphoton process. The apparatus is a tandem mass spectrometer with a radio frequency ion trap that utilizes the following scheme: the cluster ion to be studied is first mass selected; spectroscopic interrogation then occurs in the radio frequency ion trap; finally, a fragment ion is selected and detected using ion counting techniques. The vibrational spectra obtained in this manner are compared with that taken previously using a weakly bound H2 "messenger." A spectrum of H7 O + 3 taken using a neon messenger is also presented. Ab initio structure and frequency predictions by Remington and Schaefer are compared with the experimental results.

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Vibrational spectroscopy of the hydrated hydronium cluster ions H3O+·(H2O)n (n=1, 2, 3)

The nitric oxide density profile in the upper atmosphere between 70 and 110 km was measured with scanning ultraviolet spectrometers aboard two Nike-Apache rockets on February 6 and January 31, 1969. The observed nitric oxide density profile has a maximum of about 108 cm−3 at 105 km, and a minimum of about 107 cm−3 at 85 km. Photochemical equilibrium is prevalent at about 85 km while mixing dominates below that altitude. A model in which nitric oxide is formed from N(2D) atoms can explain the observed features of the height profile. The contribution of nitric oxide ionization by solar Lyman-α to the total ion production is dominant in the middle D region (below 90 km) for the solar activity level at the time of the experiments. Dissociative recombination of nitric oxide ions is the main loss process in the region above 85 km. Below that height, a faster mechanism is required.

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Rocket measurements of upper atmospheric nitric oxide and their consequences to the lower ionosphere

The ion–molecule reactions in pure nitrogen and nitrogen containing traces of water were studied with a pulsed electron‐beam mass spectrometer having a field‐free high‐pressure source. The reaction N2++2N2 = N4++N2 occurring in pure nitrogen was found to have a third‐order rate constant k = 8 × 10−29cc2molecule−2·sec−1 at 300°K and a negative temperature coefficient corresponding to an “activation energy” of − 2 kcal/mole at pressures up to 3.5 torr. The results for the reaction N++N2→N3+, investigated under the same conditions, indicated either third‐order dependence with k = 5 × 10−29cc2molecule−2·sec−1 and energy of activation − 1 kcal/mole or second‐order dependence with k = 1.3 × 10−12cc molecule−1·sec−1 with no temperature coefficient. The reaction mechanism in nitrogen in the torricelli range containing water vapor in the millitorr range was found to proceed by the following reaction sequence: N2+→N4+→H2O+→H3O+→H+(H2O)2→H+(H2O)n. The rate constants for all reactions were determined. The clustering ...

Ion–Molecule Reactions in Pure Nitrogen and Nitrogen Containing Traces of Water at Total Pressures 0.5–4 torr. Kinetics of Clustering Reactions Forming H+(H2O)n

Mass‐spectrometric studies of the ionic species formed in corona discharges in nitrogen, oxygen, and air have been carried out at water concentrations from 1.7×10−2 to 0.65 mole % and total pressures up to one atmosphere. The importance of water in this system has been demonstrated by the dominant presence of (H2O)nH+ ion clusters at water concentrations as low as 4.1×10−2 mole %. Evidence is presented for the formation (HO2)+ and (N2H)+ ions as possible intermediates in the formation of these clusters. It is argued that hydride formation by the primary ions and possibly charge‐exchange reaction with water molecules followed by proton‐transfer reactions are the mechanisms by which these clusters are produced. Simple hydration of other ionic species of the discharge, e.g., O2+(H2O)n, NO+(H2O)n, and (NO2+) (H2O)n, at water concentrations below 5.5×10−2 mole % have also been observed.

Mass‐Spectrometric Studies of Corona Discharges in Air at Atmospheric Pressures

This is a survey of the experimental observations and theories of formation of all types of sporadic E. The wind-shear theory is most likely to explain temperate-zone sporadic E. In the equatorial zone, VHF reflections are most probably due to the two-stream plasma instability, though gradient instabilities may play a part in producing the irregularities that cause HF vertical-incidence reflection. In the auroral zone, energetic particles dumped by any one of a variety of mechanisms cause ionization. This ionization has to be moved into thin layers of irregularities to cause auroral sporadic E and radio aurora reflections. Many recommendations are made to further the understanding of and the prediction of sporadic E for communication purposes.

Production and prediction of sporadic E

A quadrupole mass spectrometer system employing a liquid nitrogen chilled zeolite pump has recently been developed for sampling positive ions at altitudes above 50 km. This system was flown successfully on a Nike Cajun rocket on October 31, 1963, at local noon from Eglin Air Force Base, Florida, and has provided the first positive ion composition measurements in the D region. The predominant ions detected within the D region (64 to 82 km) were 19+, 30+, and (37±1)+, with 32+ rapidly rising above 75 km approaching the abundance of 30+ at 83 km. At 82.5 km a sharp transition occurred in the spectrums, characterized by the rapid disappearance of 19+ and 37+ and instantaneous appearance of six new ion peaks. Five of these ion peaks are suggested to be the metallic ions of sodium (23+), magnesium (24+, 25+, 26+), and calcium (40+). The metallic ions all exhibited an identical altitude profile: a 10-km- wide peak with a maximum at 95 km, a minimum at 105 km, and then a continuous increase until apogee at 112 km. Above 82 km the ions 30+ and 32+ appear to be the most predominant, although many other minor constituent ions are present.

R. S. Narcisi

Papers

Mass spectrometric measurements of positive ions at altitudes from 64 to 112 kilometers