Study of ultrafast processes in matter by means of time-resolved electron diffraction and microscopy

One of the most fundamental problems of modern natural science is the direct observation of atomic motions in the course of various processes. For this purpose, in the experiment it is necessary to provide high spatial-temporal resolution. The solution to this problem is achieved by using a pulsed electron beam of ultrashort duration to create a stroboscopic diffraction pattern in the method of time-resolved electron diffraction (TRED). Three types of experimental schemes have been developed at our lab. The experimental complex includes (i) 20-keV table-top apparatus for TRED, (ii) 75-keV ultrafast transmission electron microscope and (iii) lensless table-top device for femtosecond electron diffraction. The obtained experimental results are presented

Study of ultrafast processes in matter by means of time-resolved electron diffraction and microscopy

One of the most fundamental problems of modern natural science is the direct observation of atomic motions in the course of various processes. For this purpose, in the experiment it is necessary to provide high spatial-temporal resolution. The solution to this problem is achieved by using a pulsed electron beam of ultrashort duration to create a stroboscopic diffraction pattern in the method of time-resolved electron diffraction (TRED). Three types of experimental schemes have been developed at our lab. The experimental complex includes (i) 20-keV table-top apparatus for TRED, (ii) 75-keV ultrafast transmission electron microscope and (iii) lensless table-top device for femtosecond electron diffraction. The obtained experimental results are presented

Semi-annual variation of excited hydroxyl emission at mid-latitudes

Ground-based observations show a phase shift in semi-annual variation of excited hydroxyl (OH∗) emissions at mid-latitudes (43∘ N) compared to those at low latitudes. This differs from the annual cycle at high latitudes. We examine this behaviour by utilising an OH∗ airglow model which was incorporated into a 3D chemistry–transport model (CTM). Through this modelling, we study the morphology of the excited hydroxyl emission layer at mid-latitudes (30–50∘ N), and we assess the impact of the main drivers of its semi-annual variation: temperature, atomic oxygen, and air density. We found that this shift in the semi-annual cycle is determined mainly by the superposition of annual variations of temperature and atomic oxygen concentration. Hence, the winter peak for emission is determined exclusively by atomic oxygen concentration, whereas the summer peak is the superposition of all impacts, with temperature taking a leading role

Uneven development of economic interaction across the Finnish-Russian border

Two Finnish geographers examine the impact of the post-Cold War opening of the Finnish-Russian border on the level of economic interaction between Finland and Russia. They explore the role played by institutional and structural factors in the development of trade and foreign direct investment (FDI) between the two countries, as well as behavioral factors such as the attitudes of enterprise managers and workers. Insights into the nature of obstacles to Finnish-Russian trade and FDI are revealed by surveys of Russian workers and case studies of Finnish/Nordic companies doing business in Russia