Clifford J. Ludman

Hydrogen bonding and hydrogen motion in some alkali metal dicarboxylates studied using incoherent inelastic neutron scattering spectroscopy

Abstract Incoherent inelastic neutron scattering spectra of MH(CO 2 CX 3 ) 2 , M  Na, K; X  F, Cl are presented for energy transfers in the range 350 → 2000 cm −1 . Despite the complexity of these salts the observation of those normal modes of vibration which involve motion of the hydrogen atom is relatively simple. This is primarily due to the sensitivity of incoherent neutron scattering spectroscopy to the motion of hydrogen atoms and to the availability of an intense source of high energy neutrons. In the case of KH(CO 2 CF 3 ) 2 we were able to determine which of the two previously published assignment schemes, based on optical data, for the vibrations of the hydrogen bond is the correct one. Several different methods of predicting the intensities of neutron scattering bands were tried and the results compared with the observed values.

Some Observations on the Nature of the Calcium-Cresolphthalein Complexone Reaction and its Relevance to the Clinical Laboratory

The reasons for the non-linearity of the standard curve for the calcium-cresolphthalein complexone reaction have been investigated. Calcium forms both 1:1 and 2:1 complexes with cresolphthalein complexone; at low calcium concentrations the 1:1 complex predominates and causes non-linearity. At high calcium concentrations the cresolphthalein complexone concentration becomes limiting, resulting in flattening of the calibration curve. It is recommended that two-point calibration of the assay be performed using a low calcium standard rather than setting on the baseline.

Nuclear magnetic resonance studies of the difluoride ion. Part 2.—Difluorides of the alkali metals and alkaline earths

The 1H and 19F magnetic resonance spectra of the difluoride salts of the alkali metals, of thallium and the double fluorides of strontium and barium have been examined by pulsed methods, and the free induction decays compared with those calculated for a 3-spin, dipole–dipole broadened system. In the case of the sodium, potassium, rubidium and caesium salts, the best fit between theory and experiment is obtained for a centred difluoride ion (to within ±0.04 A in most cases) although the technique does not distinguish between a single potential energy minimum and a symmetric double one with fast transfer, except that in the latter case the two minima must be <0.18 A apart. In the case of the lithium and thallium salts and the strontium and barium double fluorides, an accurate configuration cannot be assigned, except that any displacement of the proton from centring is unlikely to exceed 0.06 A.

The i.r., Raman and inelastic neutron scattering spectra of caesium octahydridotriborate, CsB3H8

Abstract The i.r., Raman and inelastic neutron scattering spectra of CsB 3 H 8 are reported and an assignment of the internal modes of the B 3 H − 8 ion, together with some of the librational modes in the crystal is made. An attempt is made, using the simple harmonic approximation, to calculate the barrier to re-orientation in the molecule.

Incoherent inelastic neutron scattering studies of potassium bicarbonate and caesium hydrogen dinitrate

Abstract Inelastic neutron scattering spectra of KHCO3 and CsH(NO3)2 have been obtained in the region 400 → 2400 and 400 → 2800 cm−1 respectively. The in- and out-of-phase bending vibrations of the hydrogen bonds have been observed and assigned. For CsH(NO3)2 the two bending modes are closer in frequency than in KHCO3 and they are not resolved from the antisymmetric stretch.

Torsional and librational modes of the monomethylammonium ion, CH3NH+3, in its salts, studied by inelastic neutron scattering

This paper reports the direct observation, assignment and study of the torsional and librational vibrations of the ions CH3NH+3, CD3NH+3 and CH3ND+3 in the various phases of their salts with Cl–, Br–, I– and PF–6, by inelastic neutron scattering (I.N.S.). From these observations it is possible to derive a value for the torsional frequency of the “free” CH3NH+3 ion, which is intermediate between that of C2H6 and N2H2+6. It is also possible to calculate the internal and external barriers to rotation of the ion in certain of the lattices.

Inelastic neutron scattering spectra of some English coals: a preliminary study

Abstract The applications of incoherent inelastic neutron scattering (IINS) spectroscopy to the study of coal are discussed in the light of preliminary data (350–2000 cm −1 ) obtained from three English coals of various ranks.

The chlorotrimethylammonium and bromotrimethylammonium cations

Three methods are described for the preparation of the chloro- and bromo-trimethylammonium cations as a series of salts including the perchlorates and fluorosulphates. The vibrational and n.q.r. spectra are reported and discussed in relation to the bonding in the ions. Halogen and interhalogen adducts of trimethylamine have also been studied, and it is concluded that halogenotrimethylammonium cations are not present in these species.

The interaction of hydrogen chloride with ethers and other bases studied by35Cl nuclear quadrupole resonance and1H nuclear magnetic resonance

Abstract The 35 Cl NQR and 1 H NMR spectra of a series of adducts of hydrogen chloride have been measured at a variety of temperatures. The strength of the interaction of the hydrogen chloride with the base varies with the strength of the base and the variation of the 35 Cl NQR frequency provides a direct measure of this. The change is much larger than that found for the 35 Cl NQR signals in boron trichloride adducts of bases. The 1 H NMR signals follow the same trend and there is a good correlation between the two sets of measurements. The interaction of HCl with aromatic ethers occurs at the oxygen and not on the ring. Adducts of type B.2HCl have the second hydrogen chloride molecule interacting with the chlorine of the first.

Librational and torsional modes in hydrazinium, N2H2+6, salts studied by inelastic neutron scattering

Inelastic neutron scattering spectra of the hydrazinium dihalides and of hydrazinium sulphate, together with Raman and infrared data on these systems are reported. The internal torsion of the N2H2+6 ion and the whole body librations both about the N—N axis and perpendicular to it have been identified and are used to calculate the internal and external barriers to rotation. The external barriers are 20–40 % higher than for the corresponding ammonium salts and the internal barrier is considerably less than for the isoelectronic ethane molecule, leading to a predicted torsion frequency for the “free ion” of below 260 cm–1.