Bromine atom diffusion on stepped and kinked copper surfaces

In Situ Video‐STM Studies of Adsorbate Dynamics at Electrochemical Interfaces

“…In particular, pinning of sulfur adsorbates at the upper terrace side of steps was also found in the UHV-STM study on the vicinal Cu(100) surface by Masson et al [14] In that study an even lower S ad mobility than in our experiments was reported, with S ad being positional stable on the time scale of minutes, suggesting a reduced diffusion barrier in the electrochemical environment. Furthermore, adsorbate trapping at step edges was also found in several density functional theory studies, for example, for N and O on stepped Ru(0001) [29] and Br on stepped Cu(111) [30] surfaces, where it was attributed to changes in the local electronic structure of substrate atoms at steps, specifically to a positive shift of the metal d-band center. [29] The adsorbates are not completely pinned at steps, but detach with a certain probability.…”

Bridging the structure gap: Chemistry of nanostructured surfaces at well-defined defects

“…the recent review of Hammer [5]) and, on the other hand, to try using the steps as naturally nanostructured templates for the growth and self-assembling of ultra-thin films [6,7] and other nanosized structures for applications to nanoelectronics [8][9][10][11][12][13]. Among the aspects of HMI surfaces which captured the largest attention we mention: (a) the modification of the electronic properties due to the nanosized terrace width and to the reduced dimensionality of the system [14][15][16][17][18][19][20][21]; (b) the modification of the vibrational properties due to the additional phonons localized at the step edges [22][23][24][25][26][27][28][29]; (c) the roughening transition associated to step edge meandering [30][31][32][33][34][35][36]; (d) the modification of surface diffusion, impeded by the very presence of the steps and of the related Ehrlich-Schwoebel (ES) barriers [37][38][39][40][41][42]; (e) the intrinsic chirality of some step kinked surfaces, which may be of potential interest for heterogeneous asymmetric synthesis [43] and for the separation of enantiomers in enantio-sensitive reactions [44]…”

Atomic resolution ultrafast scanning tunneling microscope with scan rate breaking the resonant frequency of a quartz tuning fork resonator

“…Unfortunately, the STM is typically not considered as a real time imaging tool, because it simply cannot image fast enough. For example, bromine diffusion on flat Cu (111) surface with a barrier of E = 0.06 eV has a hopping frequency of 4.8 × 10 10 Hz at 150 K. 2 To observe this important rapid surface process in real time, we need to use a STM capable of imaging at 10 10 frames per second, which corresponds to a line scan rate of ∼10 12 lines per second (1000 GHz, in other words). Currently, the fastest STM with atomic resolution can scan at only 10.2 kHz, 3 not even close to the above requirement.…”