Ammonia Absorption Band Research Articles

A discussion on infared astronomy - On the chemistry of Jupiter's upper atmosphere

The infrared opacity of Jupiter’s upper atmosphere will be influenced by line blanketing resulting from strong absorption bands of ammonia and organic molecules. In order to calculate these effects eventually, we conduct a first investigation into the ion-molecule chemistry of the upper Jovian atmosphere. Experimental results show that intense ultraviolet radiation reacts with the constituents of the Jovian atmosphere to produce C2H4> ^2^65 a, and higher polymers. The general procedure for calculating both equilibrium and non-equilibrium abundances of these products is formulated and applied to the case of the surface passage of a satellite shadow. A specific example is made of ethylene, for which an analytical approximation gives 10 (to power of 10) molecules in an atmospheric column of 1 cm2 cross-section after a very rapid rise to equilibrium. Such a concentration of ethylene does not substantially affect the infrared radiation in the shadow.

Observations of Jupiter, Saturn, and Mercury at 1.53 Centimeters

view Abstract Citations (15) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Observations of Jupiter, Saturn, and Mercury at 1.53 Centimeters Welch, W. J. ; Thornton, D. D. ; Lohman, R. Abstract Observations of the radio emission from Jupiter, Saturn, and Mercury at 1.53-cm wavelength are reported. The disk temperature of Saturn was found to be 094 times that of Jupiter at this wavelength. Mercury, observed at an average phase angle of 125 , was found to have a disk temperature three times that of Jupiter. With Jupiter's disk temperature assumed to be 150 K at this wavelength, the temperatures of Saturn and Mercury are 141 and 450 K, respectively. The similarity in the emission from Jupiter and Saturn at this avelength can be explained if one supposes that ammonia gas is the chief source of microwave thermal radiation from both planets (due to the ammonia absorption band centered at 1.28 cm) and that the gas is saturated near the cloud tops of both planets. The possibility that emission from Saturn's rings may contribute to the radio "disk" temperature of Saturn is briefly considered. If the particles in the ring are many centimeters in diameter and perfectly absorbing, the rings contribute about 25 K to the "disk" temperature. If their mean radius is about 300 , a probable size obtained by Franklin and Cook, their microwave extinction cross-section is small and the ring particles will not emit significant microwave energy. The high disk temperature of Mercury at large phase angles is in agreement ith the observations of Howard, Barrett, and Haddock at 3 75 cm and Kellermann at 11 cm. With the radar determination that Mercury does not keep the same face to the Sun (Pettengill), these results can be understood if one supposes that the microwave emission from Mercury is similar to that from the Moon. On the other hand, the lack of disk temperature change with phase angle obtained by Epstein at 3.4 mm does not fit this interpretation. Publication: The Astrophysical Journal Pub Date: December 1966 DOI: 10.1086/148956 Bibcode: 1966ApJ...146..799W full text sources ADS |

The Photographic Infrared Absorption Spectrum of Gaseous Ammonia

The photographic infrared absorption bands of ammonia at about 10,000A, 7920A, and 6470A have been measured with greater dispersion and resolving power than hitherto. Several series have been established in the first two bands by combination principle methods, but most of the band lines have not been classified. The complexity of structure occurs probably because each observed band is a composite of several parallel-type and perpendicular-type bands; the observed series, or most of them, probably constitute parallel bands. In the pure gas, the band lines are very sensitive to pressure, and do not become at all sharp until the latter is far below one atmosphere (cf. Fig. 1). In mixtures of ammonia and air, however, the air pressure produces very little broadening. The application of the combination principle to parallel, perpendicular, and Raman bands is discussed, taking into account the effects of un-resolved but not negligible fine structure in the lines due to near-coincidence of lines of differing $K$ values. Analysis of earlier data yields a rough value for a certain small rotational coupling coefficient and for the centrifugal deformation rotational coefficient, in the normal state of ammonia.

The Ultraviolet Absorption Bands of Ammonia

The ultraviolet absorption bands of ammonia have been investigated in the region from 2400 to 1900A over a wide range of temperatures and pressures. The frequencies of a number of intense double-headed bands have been measured and an analysis of these bands is presented. The doublet separation is nearly constant and is equal to 70 ${\mathrm{cm}}^{\ensuremath{-}1}$. Only two fundamental frequencies are observed in the upper state, namely, 890 and 2720 ${\mathrm{cm}}^{\ensuremath{-}1}$. The predissociation which occurs in the excited state is discussed and accounted for by assuming that the ${{\ensuremath{\nu}}_{2}}^{\ensuremath{'}}(\ensuremath{\perp})$ type of vibration of the molecule is always unstable.

Infrared Absorption Bands of Ammonia

Eight N${\mathrm{H}}_{3}$ absorption bands have been recorded in the spectral region 1.0 to 2.0\ensuremath{\mu} with an automatic recording, prism spectrometer. The fine structure of the bands shows that they all belong to the two general types, "composite" and "double." The 1.6\ensuremath{\mu} band is composite like the 1.97\ensuremath{\mu} band first resolved by Stinchcomb and Barker. The intensity of the lines is very uniform, and the line spacing, 10.2 ${\mathrm{cm}}^{\ensuremath{-}1}$, agrees with that of the 1.97\ensuremath{\mu} band, 9.98 ${\mathrm{cm}}^{\ensuremath{-}1}$. Bands arising from changes of the electric moment parallel to the symmetry axis are double as was found in the 3\ensuremath{\mu} and 10\ensuremath{\mu} bands. The doublet spacing in the 10\ensuremath{\mu} band is 33 ${\mathrm{cm}}^{\ensuremath{-}1}$, but only 1.6 ${\mathrm{cm}}^{\ensuremath{-}1}$ in the one at 3\ensuremath{\mu}. D. M. Dennison has shown that the doublet spacing should rapidly decrease in the higher levels, and for harmonic bands the separation should be so large that they would not appear double. The 1.51\ensuremath{\mu} and 1.22\ensuremath{\mu} bands both appear as double, and have a separation of 30.3 ${\mathrm{cm}}^{\ensuremath{-}1}$ and 30.4 ${\mathrm{cm}}^{\ensuremath{-}1}$, respectively. Evidently the multiplicity of some of the higher levels is more evident than the present theory predicts.

The Parallel Type Absorption Bands of Ammonia

The form of the ammonia molecule is discussed together with the theory that all of the vibrational levels of the molecule should be double due to the two equivalent positions of equilibrium of the nitrogen atom. This theory serves to explain the doubling of the \ensuremath{\parallel} band at 10.5\ensuremath{\mu} and further predicts that the lines of the 3.0\ensuremath{\mu} band should also appear as doublets although with a much finer separation. An experimental search is made for the doubling of the 3.0\ensuremath{\mu} band using an infrared spectrometer of high resolving power. The effect is found, each fine structure line appearing as a doublet with a mean separation of about 1.6 ${\mathrm{cm}}^{\ensuremath{-}1}$. The theoretical intensities of the \ensuremath{\parallel} type ammonia bands are computed assuming that the hydrogen nucleus possesses a spin of $\frac{1}{2}(\frac{h}{2\ensuremath{\pi}})$. When these values are compared with the observed lines of the 3.0\ensuremath{\mu} and the 10.5\ensuremath{\mu} bands, a very satisfactory agreement is obtained. This agreement furnishes a strong argument for the theory of the doubling of the ammonia bands. It further proves that those states of ammonia existing in nature have vibration---rotation---nuclear spin wave functions which are antisymmetrical for an interchange of two of the hydrogen atoms.

New Absorption Bands of Ammonia, Methyl Bromide, Methyl Iodide and Carbon Dioxide in the Infrared Spectrum

Work done with the recording spectrometer at the University of Michigan has shown near the wave-length 16.1\ensuremath{\mu} an absorption band of ammonia not hitherto observed in detail, and bands due to methyl bromide and methyl iodide, near wave-lengths 16.4\ensuremath{\mu} and 18.8\ensuremath{\mu} respectively. It has also shown the strong absorption band due to carbon dioxide near 15\ensuremath{\mu} to be more complex and extensive than has previously been indicated.

Studies in the Infra-red region of the spectrum. Part IV.-Discussion of absorption bands of ammonia, phosphine and arsine

Of absorption bands in the infra-red which are partially or more completely resolved, the following four types (fig. 9) have been observed in the work of others and ourselves. Type 1 occurs in dipoles such as HC1, HBr and HF* and is absent in NH 3 , PH 3 and AsH 3 . Type 2 is characteristic of the Main Sequence of bands common to NH 3 , PH 3 and AsH 3 , and appears in the infra-red spectrum of CH 4 ; type 3, so far found only in the band of NH 3 at 10·55 ft, contains two Q branches ; while type 4 exhibits the fusion of two distinct bands, of which the zero branches in PH 3 and AsH 3 are the first members of a distinct series of harmonics.