Design and construction of a simple UHV-compatible high-pressure reaction cell

Abstract

UHVcompatible reaction cell for combined high and lowpressure studies of surface reactions Rev.A UHVcompatible round wafer heater for silicon molecular beam epitaxyThe design of a high pressure reaction cell, internal to a commercial ultrahigh vacuum (UHV) system that provides for high-pressure catalytic reaction studies with UHV surface science capabilities, is described in detail. This reaction cell is comprised of the following two elements: (a) a sample-holding flange that extends from the central manipulator and (b) a self-contained sealing "cup" that is attached to an existing 6-in. flange. This reaction cell operates hydraulically and features a small cell volume ( -45 ml) that can be pressurized up to 5 atm, sample heating and cooling capabilities, continuous gas flow or static batch modes, relatively rapid sample transfer (l-2 min) between high-and low-pressure conditions, and gas product analysis. The principle advantage of the present design over the previous ones is its compatibility with commercial UHV systems, without the requirement of bell jar reinforcement. Results of methane activation studies on a Pd(679) single crystal that exemplify the bridging of the pressure gap using this reaction cell are also briefly presented.

The dynamics of the dissociative adsorption of methane on Pt(533)

“…37 The rate of dissociation increases in the order Pd͑111͒ϽPd͑311͒ϽPd͑679͒. 38,39 However, no attempt was made to link the reaction to a specific site. In contrast to these observations, increasing the defect character of a Pt͑111͒ surface by Ar-ion bombardment appears not to influence the dissociation probability.…”

Novel recirculating loop reactor for studies on model catalysts: CO oxidation on Pt/TiO2(110)

“…Therefore, the bridge between model surfaces and real catalysts is difficult to establish, and significant effort has been devoted to the construction of reactor systems that can couple kinetic evaluation of model surfaces with UHV analysis; these designs have been summarized in a review article by Campbell 1 and in subsequent papers. [5][6][7][8] The various reactor designs each have their strengths and weaknesses, and in general they can be divided into two a) Author to whom correspondence should be addressed. Electronic mail: dachen@sc.edu.…”

“…9 Subsequent modifications of this reactor cup design have been used by a number of research groups. 6,8,[10][11][12][13][14][15][16][17] The main advantage of the reactor cup design is that high pressures of 100 atm can be achieved; the reactor cup is sealed against the sample holder by using a hydraulic piston to apply 2000 lb/in. 2 to the metal gasket seal.…”

Construction of an innovative heating apparatus for ultrahigh vacuum platens used in high pressure reaction cells

“…[1][2][3][4][5][6][7][8][9] In addition, it is common for UHV equipment manufacturers to offer commercial systems which consist of an environmental reaction cell and heating system. However, acquisition cost becomes an issue with these commercial systems and many system designs ultimately are unable to reach the temperatures necessary for catalytic research.…”