Image of the Month

PRIcon
Image of the Month
Posted Date: October 1, 2014
iotm-october-2014

Stability verification of RHK PanScan Freedom showing no influence of cryostat operation on the Si(111) 7×7 atomic structure

iotm-october-2014-1

Drift verification of RHK PanScan Freedom showing X,Y drift as low as 0.2Å/hour on the Si(111) 7×7 atomic structure at 18 K

RHK is proud to highlight the very low drift Si(111) 7×7 image acquired on our PanScan Freedom connected to a running Closed-Cycle Helium Cryostat.

The extreme stability of this microscope is demonstrated using a Si(111) 7×7 sample, showing both a high-level of isolation from the vibration of the Closed-Cycle Cryostat with the cryostat turned off in the lower half of the image and excellent drift performance as low as 0.2Å/hour.  A helium-free STM has been an elusive dream for the many researchers unable to secure a steady supply of affordable liquid helium.

RHK’s new helium-free PanScan Freedom enables every researcher to run their SPM at cryogenic temperatures, endlessly, without the trouble and expense of liquid helium.

Credits: Dr. Byoung Choi, RHK Technology

Microscope: RHK PanScan Freedom

Control System: RHK R9-STM and PMC100

+Show More
PRIcon
Image of the Month
Posted Date: August 1, 2013
institution

Atomically resolved STM images from the Pd (110)-Ic(2×2) phase together with atomic structure models. Atomic distances are 5.5 Å in (−110) and 4.8 Å in (−111). The long red arrow points along (−110).

institution

STM image of mixed the c(2×2) and q-hex phases.

Reference: J. Chem. Phys. 137, 204703 (2012); doi: 10.1063/1.4768165

Credits: Mats Göthelid, Michael Tymczenko, Winnie Chow, Sareh Ahmadi, Shun Yu, Benjamin Bruhn, Dunja Stoltz, Henrik von Schenck, Jonas Weissenrieder, and Chenghua Sun. – Materialfysik, ICT Electrum 229, Kungliga Tekniska Högskolan (KTH) and Australia Institute for Bioengineering and Nanotechnology, The University of Queensland

Microscope: RHK VT UHV STM/AFM Model UHV3500

Control System: RHK Technology SPM1000

Abstract: We use photoelectron spectroscopy, low energy electron diffraction, scanning tunneling microscopy, and density functional theory to investigate coverage dependent iodine structures on Pd(110). At 0.5 ML (monolayer), a c(2 × 2) structure is formed with iodine occupying the four-fold hollow site. At increasing coverage, the iodine layer compresses into a quasi-hexagonal structure at 2/3 ML, with iodine occupying both hollow and long bridge positions. There is a substantial difference in electronic structure between these two iodine sites, with a higher electron density on the bridge bonded iodine. In addition, numerous positively charged iodine near vacancies are found along the domain walls. These different electronic structures will have an impact on the chemical properties of these iodine atoms within the layer.

+Show More
PRIcon
Image of the Month
Posted Date: July 1, 2013
institution

12nm x 12nm STM and IETS maps simultaneously acquired on the surface of the 9 ML Pb island at a 1 nA tunneling current.The STM image (a) was obtained at a tunnel bias of 750 mV. The IETS image (b) was acquired at a tunnel bias of 9 mV.(c) Cross section of the IETS image in (b)

institution

The inelastic electron tunneling spectrum measured on top of the 9 ML Pb island. Resonant phonon emission peaks develop at a 9 mV tunnel bias. Inset: tunnel I-V curve for the same island measured in a broader bias range.Steps on this curve are due to QW resonances from transverse electron interference. The decrease of the barrier height at large bias was compensated by a slow increase of a tunneling gap, at a rate of 0.4 Å per |V|.

Reference:
PhysRevLett.109.166402 DOI 10.1103/Physlet.109.166402

Credits:
Igor Altfeder, K. A. Matveev, A. A. Voevodin

Microscope:
RHK Technology VT UHV STM Model UHV300

Control System:
RHK Technology SPM 1000

Abstract:
Thin Pb films epitaxially grown on 7 7 reconstructed Si(111) represent an ideal model system for studying the electron-phonon interaction at the metal-insulator interface. For this system, using a combination of scanning tunneling microscopy and inelastic electron tunneling spectroscopy, we performed direct real-space imaging of the electron-phonon coupling parameter. We found that ! increases when the electron scattering at the Pb=Sið111Þ interface is diffuse and decreases when the electron scattering is specular. We show that the effect is driven by transverse redistribution of the electron density inside a quantum well.

+Show More
PRIcon
Image of the Month
Posted Date: June 1, 2013
institution

STM image (0.7 V/2 pA) showing two CoPc islands with kinks in different directions of the CoPc lattice. (b) Possible model to explain the kinks, where the shifted row jumps to the neighboring equivalent site. Image acquired at 50K.

institution

150 × 150 nm2 STM image (100 pA/0.16 V) of graphene on the Ir(111) surface before CoPc deposition. (inset) Atomically resolved STM image of the moiré (1 nA/0.1 V). The hexagonal pattern is the moiré caused by the lattice mismatch between graphene and Ir.

Reference:

The Journal of Physical Chemistry C – dx.doi.org/10.1021/jp306439h | J. Phys. Chem. C 2012, 116, 20433−20437

Credits:

Sampsa K. Hamalaïnen, Mariia Stepanova, Robert Drost, Peter Liljeroth, Jouko Lahtinen, and Jani Sainio – Department of Applied Physics, Aalto University School of Science in Otakaari, Finland.

Microscope:

RHK Technology VT UHV 7500 Scanning Tunneling Microscope (STM)

Control System:

RHK Technology SPM 1000 Control System

Abstract:

We have studied the adsorption and self assembly of cobalt phthalocyanine (CoPc) on epitaxial graphene grown on iridium (111) by scanning tunneling microscopy (STM), Auger electron spectroscopy, and low energy electron diffraction (LEED). CoPc deposited on graphene/Ir(111) at room-temperature self-assembles into large, well-ordered domains with a nearly square unit cell. On the basis of the observed LEED pattern and STM images, a detailed structure for the overlayer is proposed. Despite the corrugation of the moiré pattern of graphene on Ir(111), its hexagonal symmetry is not translated to the CoPc layer. This is in contrast to systems with stronger graphene−metal interaction that makes graphene on Ir(111) a convenient, clean, and well defined model system for studying molecular doping of graphene.

+Show More