E. E. Ylinen

Bio: E. E. Ylinen is an academic researcher from University of Turku. The author has contributed to research in topics: Spin–lattice relaxation & Relaxation (NMR). The author has an hindex of 6, co-authored 8 publications receiving 97 citations.

Proton spin-lattice relaxation and ammonium tunnelling in (NH4)2ZnCl4

Abstract: Effects of rotational tunnelling on the proton spin-lattice relaxation were studied in (NH4)>ZnCl4 as functions of both temperature and the resonance frequency. Several tunnelling-related TI minima were found. At 20 K the tunnel frequencies were deduced to be 13 MHz, 24.5 MHz, 37 MHz and 51.5 MHz corresponding to the separation between the nondegenerate and the doubly degenerated T levels, to the T-A splittings and to the E-A splitting, respectively. The smallest tunnel frequency (13 MHz) was observed to branch into two above 20 K. The higher frequency branch could not be detected above 26 K because of a broadening of the corresponding TI minimum. The broadening suggests a presence of two motions which was supported by experiments on the spin-lattice relaxation of the dipolar energy.

Rotational tunneling effects in 2H‐NMR spectra of polycrystalline (ND4)2SnCl6

Abstract: Rotational tunneling effects are analyzed in 2H‐NMR spectra of deuterated ammonium ions in powders. The spectra are generally composed of a strong central line from A symmetry species and weaker T sidebands. At a high magnetic field (∼6.5 T) the central line contains well‐resolved doublets. Their separations supply a direct measure of the rotational tunneling frequency νt in the range 0.1<νt<6 MHz. At low magnetic fields the spectra depend both on νt and the Larmor frequency ν0. Level crossing related effects may be detected in a ±0.75 or ±0.35 MHz range around that Larmor frequency which is equal to νt or 1/2 νt, respectively. Generally, only the fitting of the theoretical spectra to those measured at different ν0 allows an estimation of the tunneling frequency. The measurement of νt up to about 20 MHz becomes thus possible. The theoretical predictions are verified by results on a (ND4)2SnCl6 powder sample. High and low field spectra lead to slightly different values for the tunneling frequency at 4.2 K ...

2H-NMR study of ammonium ion rotational tunneling and reorientation in (ND4)2SnCl6 single crystal: I. Tunneling frequency measurements

Abstract: Theory of2H-NMR spectra is developed for a ND4+ ion. Quadrupole and dipole-dipole interactions for four deuterons of the tetrahedral ion as well as the rotational tunneling are taken into account. Features in the single crystal spectra at the high magnetic field of 6.7 T are analyzed. Their central doublets (±5 kHz range around the Larmor frequency) are attributed to theA symmetry species and exhibit sensitivity to theA−T tunneling frequencyvt. This allows the measurement ofvt in a wide rangevt <10 MHz. The shape of sidebands (±140 kHz range) is related to the T levels structure. Theoretical predictions are verified on a (ND4)2SnCl6 single crystal at 44 MHz. The tunneling frequency at temperatures below 10 K equals 7.5 MHz, which is about 100 times smaller than for (NH4)2SnCl6.vt was measured up to 40 K. At still higher temperatures motional narrowing effects were observed for theA spectral components preventing the determination ofvt.

A level-crossing relaxation study of ND4+ ion tunnelling frequencies in ND4ClO4 and (ND4)2PtCl6

Abstract: Deuteron spin-lattice relaxation time T1 was measured in ND4ClO4 and (ND4)2PtCl6 at frequencies from 4 to 7 MHz and for the temperature range from 1.7 to 40K. Shallow level-crossing minima were revealed in the frequency dependence, allowing the tunnelling splittings between the A and E symmetry levels to be estimated as about 6.2 MHz and 10.8 MHz for ND4ClO4 and (ND4)2PtCl6, respectively. The shape of the free induction decay was observed to depend on the resonance frequency and was found to be much shorter at the level-crossing minima for ND4ClO4. Activation energies of 3.2 and 3.6 kJ mol-1 were obtained for ND4ClO4 and (ND4)2PtCl6 respectively.

Combined solid-state NMR, FT-IR and computational studies on layered and porous materials.

Abstract: Understanding the structure–property relationship of solids is of utmost relevance for efficient chemical processes and technological applications in industries. This contribution reviews the concept of coupling three well-known characterization techniques (solid-state NMR, FT-IR and computational methods) for the study of solid state materials which possess 2D and 3D architectures and discusses the way it will benefit the scientific communities. It highlights the most fundamental and applied aspects of the proactive combined approach strategies to gather information at a molecular level. The integrated approach involving multiple spectroscopic and computational methods allows achieving an in-depth understanding of the surface, interfacial and confined space processes that are beneficial for the establishment of structure–property relationships. The role of ssNMR/FT-IR spectroscopic properties of probe molecules in monitoring the strength and distribution of catalytic active sites and their accessibility at the porous/layered surface is discussed. Both experimental and theoretical aspects will be considered by reporting relevant examples. This review also identifies and discusses the progress, challenges and future prospects in the field of synthesis and applications of layered and porous solids.

Inelastic incoherent neutron scattering study of the methyl rotation in various methyl halides

Abstract: The inelastic incoherent neutron scattering technique has been applied in an energy range from 0.4 μeV to 60 meV to measure the rotational excitations of the methyl groups in polycrystals of CH3I, CH2DI, CD3I, CH3Br, CD3Br, and CH3Cl in a temperature range 5

2D NMR and 35Cl nuclear-quadrupole-resonance study of ammonium-ion motion and phase transitions in natural and deuterated (NH4)2TeCl6.

Abstract: The $^{35}\mathrm{Cl}$ nuclear quadrupole resonance (NQR) and the quadrupole perturbed $^{2}\mathrm{D}$ NMR have been investigated in (${\mathrm{ND}}_{4}$)${\mathrm{TeCl}}_{6}$ in the temperature range 4.2\char21{}85 K. The $^{2}\mathrm{D}$ spin-lattice relaxation rate shows a classical maximum at about 80 K and a broad peak at about 25 K, which is attributed to the influence of a phase transition at the same temperature. An extra contribution to the chlorine NQR spin-lattice relaxation rate is observed near the cubic-to-trigonal transition at 85 K. The disappearance of the NQR signal before the second transition at about 42 K is accompanied by a divergence of the spin-spin relaxation rate. The results are discussed in terms of a localization of the deuterium in a triangle-shaped potential well in the plane perpendicular to the N-D bond direction.