Sample mounting and transfer for coupling an ultrahigh vacuum variable temperature beetle scanning tunneling microscope with conventional surface probes

Nafisi, Kourosh; Ranau, Werner; Hemminger, John C.

doi:10.1063/1.1327308

Cited by 4 publications

(2 citation statements)

References 13 publications

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“…A second method exposes the hydrocarbon to a sample which is resting at an elevated temperature . The dehydrogenation of aromatics, such as naphthalene, on Pt(111) leads to unstructured patches of carbon. − On the other hand, dehydrogenation of ethylene on Pt(111) converts in a distinct manner into individual carbon particles and eventually graphite by way of a uniform intermediate species, ethylidyne. , Land et al demonstrated that an initial step in the thermal dehydrogenation of the ethylidyne surface species on Pt(111) resulted in the formation of well-defined carbon clusters …”

Section: Introductionmentioning

confidence: 99%

Scanning Tunneling Microscopy Investigation of the Conversion of Ethylene to Carbon Clusters and Graphite on Pt(111)

2009

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The dehydrogenation of ethylene on Pt(111) was studied by scanning tunneling microscopy (STM) under ultra-high vacuum conditions. Previous experiments have shown that thermal dehydrogenation following saturation exposure of ethylene on Pt(111) resulted in the formation of well-defined carbon clusters. The aggregation to form the carbon clusters leaves open Pt areas that could be available for additional adsorption. It had not been previously determined whether the adsorption and dehydrogenation of additional ethylene would lead to the growth of the initial clusters or the nucleation of additional clusters of the same size. The present study confirms previous reports that the initial carbon clusters are 15 ( 2 Å in diameter, 2.5 ( 0.3 Å in height, and contain an average of 34 ( 9 carbon atoms per cluster. We show that exposing this surface to additional ethylene at room temperature and annealing leads to an increase in the number of particles of the same size, with no growth in size of the initial particles. Dosing and dehydrogenation/annealing cycles were repeated until the dehydrogenation activity of the Pt(111) surface was completely suppressed, which occurred after the fourth such cycle. Continued cycling leads to the beginning of the formation of a graphite adlayer on the platinum, presumably via agglomeration of the clusters at a high cluster density.

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Section: Introductionmentioning

confidence: 99%

Scanning Tunneling Microscopy Investigation of the Conversion of Ethylene to Carbon Clusters and Graphite on Pt(111)

2009

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“…5 Mendus and Chambers 6 describe a docking station for a standard Omicron sample plate which allows heating of the sample via resistance heating and electron bombardment heating. In the concept described by Nafisi et al 7 a heating filament is integrated directly into the sample holder, but the mobility of the sample holder is limited due to the cables attached to it. Aristov and Ionov 8 developed a cryomanipulator, cooled by liquid helium, which furthermore functions as a docking station for a mobile sample holder.…”

Section: Introductionmentioning

confidence: 99%

Mobile sample holder applying multiple heating systems with a variable heating and cooling rate

Leist

Winkler

Büssow

et al. 2003

Review of Scientific Instruments

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A mobile sample holder applying multiple heating systems with variable heating and cooling opportunities will be presented. Design details and initial results will be given. The whole sample holder system consists of two units: the docking station ͑one͒ on which the mobile sample holder together with its mobile sample plate ͑two͒ is mounted. Some of the significant advantages of this system in comparison with others are as follows. The docking station can be attached to the cold face of continuous flow cryostats or reservoir cryostats thus enabling cooling via, e.g., liquid nitrogen. The modular design of the sample holder allows it to be individually customized to fulfill specifically required heating methods ͑e.g., resistance heating, electron bombardment heating, direct heating, conductivity heating͒ for different sample materials ͑insulators, semiconductors, conductors͒. Furthermore, the variable setup allows for optimization with respect to cooling or heating properties as well as the incorporation of samples with different sizes and shapes. Even commercially available sample carrier systems can be combined with this sample holder design and still retain all heating and cooling features.

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Ex‐situ surface preparation and analysis: transfer betweenUHVand electrochemical Cell

Hoster¹,

Gasteiger²

2010

Handbook of Fuel Cells

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The further optimization of electrode materials for fuel cells in laboratory studies offers two main approaches: (i) improving the understanding of the microscopic electrode processes by observation with in‐situ and ex‐situ methods; and (ii) the systematic compositional and structural variation of surfaces to create model electrodes for electrocatalytic measurements. The ultra high vacuum (UHV) environment offers unique possibilities for both surface preparation and analysis and has thus been used extensively in recent electrocatalytical research work. At the same time, methods allowing the in‐situ observation of electrochemical processes has also gone through impressive advances in recent years, and in many cases it has been found that earlier ex‐situ results obtained in UHV needed to be revised due to changes of the electrode surfaces during the transfer into UHV. In the following we will discuss some of the most frequently applied ex‐situ methods in electrocatalytic research and review some of the important aspects concerning the reliability of the resulting data. Utilizing a number of examples, we will demonstrate how such combined UHV electrochemistry experiments can be technically realized, including a discussion of commonly encountered practical problems. We will further point out the advantages offered by the electrocatalytical characterization of UHV designed and UHV characterized model electrodes. In our opinion, this is a very promising approach to UHV/electrochemistry experimentation: on the one hand, the uncertainties due to the transfer between UHV and electrochemical environment are less significant compared to emersion experiments of adsorbed adlayers; on the other hand, well‐established UHV preparation techniques combined with structural characterization tools (atomic force microscopy (AFM)/scanning tunneling microscopy (STM)) provide the possibility of precisely tailoring defined model electrodes. Some examples from research on anode catalysts are given to illustrate this unique capability of UHV electrochemistry setups as powerful tool for the systematic tailoring of model electrodes.

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Sample mounting and transfer for coupling an ultrahigh vacuum variable temperature beetle scanning tunneling microscope with conventional surface probes

Cited by 4 publications

References 13 publications

Scanning Tunneling Microscopy Investigation of the Conversion of Ethylene to Carbon Clusters and Graphite on Pt(111)

Scanning Tunneling Microscopy Investigation of the Conversion of Ethylene to Carbon Clusters and Graphite on Pt(111)

Mobile sample holder applying multiple heating systems with a variable heating and cooling rate

Ex‐situ surface preparation and analysis: transfer betweenUHVand electrochemical Cell

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