Alkali-metal-affected adsorption of oxygen on W(110)

Vibrationally promoted emission of electrons from low work function surfaces: Oxygen and Cs surface coverage dependence

“…These trends are similar to those observed when the work function is monitored versus oxygen exposure for W͑110͒ surfaces with varying initial Cs doses. 5,8 In control experiments without oxygen exposure carried out in our lab, the electron emission from vibrationally excited NO molecules changed at a much slower rate than that shown in Fig. 5.…”

“…One way to accomplish this is by exposure of oxygen to the Cs/ Au surface. 5,6 An UHV leak valve allows for the introduction of O 2 gas at a constant pressure of approximately 4 * 10 −9 mbar. The particle emission was monitored as a function of oxygen exposure and compared to the photoemission from a He-Ne laser also as a function of oxygen exposure.…”

“…By reducing the metals work function, this situation changes. Alkali metals have work functions on the order of 1.9-2.5 eV 4 and a small coverage of an alkali metal on a transition metal produces a surface with an even lower work function [5][6][7][8] which is significantly lower than the vibrational energy of NO in v = 18.…”

Electron emission in collisions of slow rare gas ions with partially cesiated W (110)

“…A correction has been applied to the spectra in order to compensate the energy dependence (ocl/Ekin) of the ESA's transmission. The change of the position of the low-energy cut-off of the spectra in all cases reflects the change of WF upon exposure to alkali atoms which leads to a decrease of the work function from its value of the clean W(110) surface (5.3 eV) to a minimum value (around 1.5 eV) around 0.65 ML followed by a rise of the work function towards its value (around 2 eV) for the full monolayer coverage [22,23].…”

“…The partial alkali coverage (in units of completed monolayers (ML) at room temperature) is determined by work function (WF) measurements. The relation between WF and the alkali coverage is established by combining WF measurements with AES results [22,23]. The cleanliness of the W(110) crystal prior to the preparation of the alkali adlayer is checked by AES and WF measurements.…”