Using a time-of-flight technique we have investigated the backscattering of 5 keV ${\mathrm{Ar}}^{2+}$ and ${\mathrm{Ar}}^{11+}$ projectiles from Au(110). A strong dependence on target azimuth is found for the neutral flux resulting from (quasi)binary projectile collisions with target atoms, while for the charged components only a weak dependence is seen. A deconvolution of the observed dependences based on trajectory simulations clearly shows site-specific neutralization differences between the various possible binary collisions occurring with surface atoms. Such differences must be properly accounted for in order to permit meaningful comparison with theory.

Exact analysis of spin crossover in infinite elastic chain of two-spin exchange clusters was performed theoretically beyond mean-field approximation. Statistical mechanics of the system was exactly calculated by means of the transfer matrix technique. A possibility of spin-Peierls-like magneto-structural transition in a one-dimensional chain was shown as a result of interrelation of spin and elastic subsystems of the chain. The importance of the boundary conditions for spin crossover to occur was shown. The smoothness of spin crossover depends on the parameters of chain elasticity and the crossover position on the temperature scale is defined by the dependence of exchange integral on the cluster deformation. The proposed model qualitatively describes the main scenario of spin crossover effect in the chain polymer heterospin complex of copper(II) hexafluoroacetylacetonate with methyl pyrazol-substituted nitronyl nitroxide containing two-spin exchange clusters.

Methods for the synthesis of binuclear [Cu(hfac)₂L^Et]₂ and tetranuclear [[Cu(hfac)₂]₄(L^Et)₂] heterospin compounds based on copper hexafluoroacetylacetonate [Cu(hfac)₂] and 2-(4-ethylpyridin-3-yl)-4,5-bis(spirocyclopentyl)-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (L^Et), were developed. The crystals of the complexes are elastic and do not crash during repeated cooling–heating cycles. It was found that a singlet–triplet conversion occurred in all of the {Cu(II)–O•–N<} exchange clusters in the molecules of the binuclear [Cu(hfac)₂L^Et]₂ which led to spin coupling with cooling. The transition occurred in a wide temperature range with a maximum gradient ΔχT at ≈180 K. The structural transformation of the crystals takes place at T < 200 K and is accompanied by the lowering of symmetry from monoclinic to triclinic, twinning, and a considerable shortening of the Cu–O_NO distance (2.19 and 1.97 Å at 295 and 50 K, respectively). For the tetranuclear [[Cu(hfac)₂]₄(L^Et)₂], two structural transitions were recorded (at ≈154 K and ≈118 K), which led to a considerable change in the spatial position of the Et substituent in the nitronyl nitroxyl fragment. The low-temperature process was accompanied by a spin transition recorded as a hysteresis loop on the χT(T) curve during the repeated cooling–heating cycles (T½↑ = 122 K, T½↓ = 115 K). This transition is unusual because it causes spin coupling in half of all of the {>N–•O–Cu²⁺} terminal exchange clusters, leading to spin compensation for only two paramagnetic centers of the six centers in the molecule.