Microwave spectra for eight isotopic species of cis and trans nitroils acids are reported. The planarity of both isomers has been accurately established on the basis of the inertial defects. Accurate structures, electric dipole moments and quadrupole coupling constants at nitrogen have been determined for both isomers. The structure of cis nitrous acid is found to be :104.0 and L O N O = 113.6", and for trans nitrous acid: 0-H = 0.958, N--O(H) = 1.432, N-0 = 1.170& LNOH = 102.1 and L O N O = 110.7". Stark effect measurements yield the following values for the components of the dipole moment for cis nitrous acid : pu = 0,306, IJ-6 = 1.389 and the total dipole moment p = 1.423 rf0.005 D. Previous investigations of the Stark effect in the trans isomer have been refined to give vu = 1.378, pb= 1.242 and p = 1.855f0.016D. Orientation of the dipole moment has been established for both isomers from isotopic measurements, despite a moderately large vibrational change in pu for trans DN02. Quadrupole coupling constants in the principal inertial axis system have been determined for cis nitrous acid to be : xaU = 2.05, Xbb = -5.83 and xcc = 3.78 MHz, and for trans nitrous acid: Xaa = 1.73, Xbb = -5.28 and xcc = 3.55 MHz. hypothetical Av *

Centrifugal distortion shifts in the microwave spectra of cis and trans nitrous acids and their deuterated species have been analyzed using the first-order treatments of Hill and Edwards, and Watson. The two methods are in close agreement for the ground vibrational state of planar molecules. Centrifugal distortion constants thus derived have been used, together with the infra-red fundamentals and their isotopic shifts, to determine the quadratic potential function for each isomer.Eleven out of a possible sixteen force constants have been determined as follows (in mdyn A-') : for cis nitrous acid, fi ,(OH) = 6.55, fz2(N=O) = 11.18, fss(N-0) = 2.73, f44(NOH) = 0.88, f55(ONO) = 2.46, f 2 3 = 1.80, fZ4 = 0.22, f34 = 0.53, f 3 5 = 0.35, f45 = 0.18 and fs6(torsion) = 0.167; and for trans nitrous acid, f l l = 7.18, f z 2 = 12.28, f 3 3 = 2.22, f44 = 0.76, fS5 = 2.45,

The concept of a portable gas chromatography/ion mobility spectrometry (GC/IMS) device Is Introduced. The potential of the GC/IMS unit Is Investigated for the separation and characterization of vapor mixtures of various chemical classes. Parameters such as Internal cell pressure, GC column flow rate, and column temperature were varied to determine the effects on speed and resolution for separating and characterizing mixtures. It was generally found that by reducing both the Internal IMS cell pressure and the Isothermal GC column temperature, the peak widths, retention times, and peak overlap could be varied for different classes of analytes. The GC/IMS system shows versatility In the various compound classes that can conveniently be analyzed by a hand-portable version. Mixtures Included phosphonates, phosphates, alkyl ketones, and chlorophenols with total separation times In the 7-s to 2-min time range. Positive or negative Ion polarities In IMS were used depending upon the functional group.

No abstract

No abstract