Multi-temperature diffraction

EXAFS (Extended X-ray Absorption Fine Structure) measurements using synchrotron radiation have been successfully applied to the determination of structural details of SCO systems and have been particularly useful when it has not been possible to obtain suitable crystals for X-ray diffraction studies. Perhaps the most significant application has been in elucidating important aspects of the structure of the iron(II) SCO linear polymers derived from 1,2,4-triazoles [56]. EXAFS has also been applied to probe the dimensions of LIESST-generated metastable high spin states [57]. It has even been used to generate a spin transition curve from multi-temperature measurements [58]. 

Tanaka K, Onuki Y (2002) Observation of 4f electron transfer from Ce to Bg in the Kondo crystal CeBe and its mechanism by multi-temperature X-ray diffraction. Acta Crystallogr B 58 423 36... 

Multi-temperature X-ray diffraction data for a series of spin-crossover complexes differing in cooperativity indicates that the molecule and crystal volume variations upon spin conversion are similar in all the cases irrespective of the cooperative nature of the spin conversion [47]. So, a systematic structural analysis of specifically designed spin-crossover compounds should be of utmost importance to establish correlations between intermolecular interactions and cooperativity. The comparative structural study of [Fe(phen)2(NCS)2] and [Fe(btz)2(NCS)2] where btz = 2,2 -bi-4,5-dihydrothiazine (Figure 10) represents the sole example so far reported oriented in this direction [48,49]. It illustrates the dependence of the nature of the phenomenon on the efficiency of the intermolecular contacts in transmiting the intramolecular reorganization upon spin conversion. 

Kastbjerg, S., Uvarov, C. A., Kauzlarich, S. M., Nishibori, E., Spackman, M. A., Iversen, B. B. (2011). Multi-temperature synchrotron powder x-ray diffraction study and hirshfeld surface analysis of chemical bonding in the thermoelectric zintl phase Ybi4MnSbn. Chemistry of Materials, 23, 3723-3730. 

Catalyst surface areas were measured using the multi-point BET method on a Carlo-Erba Ins. Sorpty 1750. Before the measurements, the samples were heated under dynamic vacuum at 573 K for 1 h in order to remove adsorbed water and impurities. Measurements were made at liquid nitrogen temperature with nitrogen as the adsorbate gas. Powder X-ray diffraction measurements were performed on a Siemens Model D-500 diffractometer with Co Kc monochromatic radiation (X = 1.78901 A) and the high resolution electron microscopy was carried out on a Topcon EM-002B microscope. To prevent artefacts no solvents were used in the preparation and mounting of samples for HRTEM. 

Fig. 11(a) shows the AFM image of an 11-layer mixed-stack CT film of octadecyl-TCNQ and (Me)2P scanned at room temperature with a scan area of 2x2 pm2 [29]. It can be seen from the image that the CT film consists of platelet microcrystal domains of a few micrometers in size in which a multi-layered structure with many steps is observed. An analysis of the cross-sectional profile revealed that the layered platelet microcrystal domains have a step of 3.3 nm thickness [29]. This is in good agreement with the d value measured by the X-ray diffraction method [28]. Therefore, it seemed that the X-ray diffraction peaks originate from the multi-layered structure inside the domains. Each layer in the domains apparently consists of biomolecular layers of octadecyl-TCNQ and (Me)2P because the layer thickness of 3.3 nm is larger than the molecular length (3.0nm) of octadecyl-TCNQ. The biomolecular layer structure also supports that the CT film is in a mixed-stack pattern. 

The e - y transition boundary was determined by measuring the resistance changes during the transition in a high-compression belt apparatus (Bundy, 1965) and in an internally heated diamond-anvil cell (Boehler, 1986 Mao et al, 1987). The boundary was also determined by in situ X-ray diffraction measurements in an internally heated diamond-anvil cell (Boehler, 1986 Dubrovinsky et al, 1998), in a laser-heated diamond-anvil cell (Shen et al, 1998), and in a multi-anvil apparatus (Funamori et al, 1996 Lfchida et al, 2001). The boundaries determined by Mao et al. (1987), Shen et al (1998), and Lfchida et al (2001) are in good agreement, but are all at —75 K higher temperature (or —2 GPa lower pressure) than the boundary determined by Funamori et al. (1996), Boehler (1986), and Bundy (1965). 

Parise JB, Hriljac JA, Cox DE, Corbin DR, Ramamurthy V (1993) A high resolution synchrotron powder diffraction study of frans-stilbene in zeolite ZSM-5. J Chem Soc, Chem Comm 226-228 Parise JB, Weidner DJ, Chen J, Liebermann RC, Chen G (1998) In situ studies of the properties of materials under high-pressure and temperature conditions using multi-anvil apparatus and synchrotron... 

The volume—pressure relationship for e-Fe has been determined up to 300 GPa at room temperature (Figure 3 Mao et al., 1990). Determining the temperature dependence of the bulk modulus of iron is crucial for accurate comparison between the density of iron and that of the iimer core. Several in situ X-ray diffraction studies in the diamond-anvil cell (Huangeta/., 1987 Dubrovinsky eta/., 1998, 2000) and in the multi-anvil apparatus (Funamori et al., 1996 Uchida et al., 2001) have provided limited data on the thermal expansion of e-Fe at high pressures. The data of Dubrovinsky et al. 

Fig. 7 a. Time-resolved small-angle diffraction from a multi-lamellar aqueous dispersion (c p 0.2) of dipalmitoyl-phos-phatidylcholine (DPPC) during a temperature-jump and -drop experiment. The respective temperature courses are shown in the inserts, b Contour-line plot of the intensities obtained in the heating-experiment, c Temperature-dependence of the recovery rates of the phase, on the equilibration temperature, upon cooling from 37 °C. (From Ref. 74, with permission)... 

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