Micro–Raman Spectroscopy of Diamonds from JaH 054 and Sahara 98505 Ureilites, Statistic Research

In this paper Raman spectra of diamonds from two different ureilites, JaH 054 and Sahara 98505, were measured. Obtained results for both ureilites showed the Raman shift ranged between 1321 cm -1 and 1336 cm -1 for JaH 054 and between 1329 cm -1 and 1336 cm -1 for Sahara 98505. FWHM parameter (full width at half maximum) varied also in wide range especially for Sahara 98505. Raman imaging was done for JaH 054 sample and diamonds of different Raman shifts (1321 cm-1, 1328 cm-1, 1330 cm-1) were found in few tens (im sized area of carbon vein. Raman peaks of ureilitic diamonds were compared with literature data of laboratory diamonds produced under high pressure, under low pressure with MW PACVD method and with other ureilites. Presented research showed that even in highly shocked ureilites Raman shift versus FWHM parameter plots are similar with CVD diamonds for ureilites. However, the origin of diamonds in ureilites is not explained based on the obtained results, close coexistence of different diamonds in investigated ureilites suggests that the mechanism of diamond creation in meteorites was very complex and could be multi-step process

Transparent and air stable organic field effect transistors with ordered layers of dibenzo[d,d]thieno[3,2-b;4,5-b′]dithiophene obtained from solution

International audienceIn a search for solution processable and stable p-type semiconductors an analogue of pentacene namely dibenzo[d,d]thieno[3,2-b;4,5-b′]dithiophene (DBTDT) - was tested as an active layer in organic field effect transistors (OFETs). It was found that thin, continuous and transparent films of DBTDT can be obtained with the help of solution based zone-casting technique. This deposition technique allows one to produce highly oriented crystalline layers of DBTDT showing similar molecular arrangement as that of a single crystal. The zone-cast layers of DBTDT were successfully applied in a fabrication process of OFETs with Parylene C® used as the gate dielectric. The best parameters are exhibited by the devices with the bottom-gate, top contact configuration: charge carrier mobility of ca 0.02 cm2/Vs and threshold voltage of ca −50 V and performance of these OFETs remains unchanged after 1 months storage in air