- Email: [email protected]
Construction of an electron analyzer with a wide acceptance solid angle
Surface Science 600 (2006) L33–L37 www.elsevier.com/locate/susc
Surface Science Letters
Construction of an electron analyzer with a wide acceptance solid angle Daisuke Sakai a,*, Daisuke Miura a, Takeshi Nakajima a, Tsuyoshi Ishikawa a, Chuhei Oshima a, Hideo Iwai b, Yoshimasa Nihei c a
Institute of Material Science and Technology, Waseda University, 2-8-16 Nishiwaseda, Shinjuku-ku, Tokyo 169-0051, Japan b ULVAC-PHI, Inc., 370 Enzo, Chigasaki-shi, Kanagawa 253-0084, Japan c Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-8510, Japan Received 4 September 2005; accepted for publication 21 November 2005 Available online 27 December 2005
Abstract We have developed a new electron energy analyzer with a large solid angle of 0.14p, which is comparable to that of cylindrical mirror analyzer. Typical energy resolution was DE/E0 0.016 for the aperture of 1 mm and central radius of 100 mm, and typical angular resolution was less than 0.5. 2005 Elsevier B.V. All rights reserved. Keywords: Auger electron spectroscopy (AES); Electron energy loss spectroscopy (EELS); Electron spectroscopy; Low energy electron diffraction (LEED)
1. Introduction Electron energy analyzers are used for surface analysis. For X-ray photoelectron spectroscopy, concentric hemispherical analyzer (CHA) is widely used, and Auger electron spectroscopy (AES) employs cylindrical mirror analyzer (CMA) because of high signal intensity [1,2]. Some of CHA also have a function of angle-resolved measurement, although the measurement is time-consuming. In contrast, CMA is not suitable for angle-resolved measurement, because electrons entering with definite pass energy in the directions around 42 from the central axis are integrally detected and it makes difficulty of angle-resolved measurements in any directions. An electron energy analyzer, equipped with both wide acceptance angle such as that of CMA and angle-resolved measuring such as that of CHA, has been desired. Daimon et al. constructed a display-type analyzer, the features of which are no angular aberration in the ideal electric field case, 2p sr solid angle, and capability of angle-resolved analysis [3]. However, this analyzer had *
Corresponding author. E-mail address: [email protected] (D. Sakai).
0039-6028/$ - see front matter 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.susc.2005.11.028
weakness. Namely, the energy resolution depends on incident directions, and in the certain directions the function disappears [4]. Hence, additional electrodes had to be inevitably installed for function of low and high energy pass filters [5]. As a result, the principle of the energy analyzer’s was the same as that of a display-type analyzer developed by Eastman et al. [6]. In this work, we limited the acceptance angle of the display type analyzer, and realized the spatial-dispersive type analyzer, which works in such a way as CHA and CMA. The structure of our spectrometer is simple. The acceptance solid angle is comparable to that of CMA, being three orders of magnitude wider than that of conventional CHA. This can shorten the measurement time down to less than a thousandth of that of conventional CHA. In this paper, we report the trajectory calculations, the structure and the design, and the experimental results for evaluating the performance. 2. System configuration A schematic diagram of the analyzer constructed in this work is shown in Fig. 1. It consists of pre-retard optics, spherical deflector, and a screen with MCP. The pre-retard
CE RF A LE CE TT S ER CIE S N
D. Sakai et al. / Surface Science 600 (2006) L33–L37 Outer spherical electrode
E/E0 = 0.95 E/E0 = 1.00 E/E0 = 1.05
Aperture A 20˚
20˚
O
Three guard rings MCP Screen
20˚
α S
Pre–retard optics Electron gun
Specimen
(a)
Inner spherical electrode
Fig. 1. A schematic diagram of the analyzer constructed in this work. The point S is the specimen, the point A is the aperture, and the point O is the middle point of the line AS as OS = OA = 50 mm. The angle a is incidence angle. The thick curve is a trajectory of an electron emitted from the point S with proper energy.
optics is made up of two concentric spherical-shaped meshes. Transmission of electrons through each mesh is 88%, and high transmission of 88% through these two meshes was established, because the hole-positions of both the meshes are aligned. The pre-retard optics forms retarding field between the two meshes as high-pass filter, and improves the energy resolution by reducing the pass energy of incoming electrons. The spherical deflector consists of concentric spherical outer and inner electrodes with 60 mm and 120 mm radii, guard rings and an aperture of 1 mm diameter. Electrons entering to the spherical deflector pass through spherical-shaped meshes on the inner electrode. The point O in Fig. 1 is the middle point of the line AS as OS = OA = 50 mm, and it is also a center of equi-potential lines (1/r) generated between the inner and outer electrodes. We installed an electron gun with ZrO/W source together with electro-static lens manufactured by APCO Inc.; the spatial resolution of SEM image was 50 nm. The working principal of the analyzer is as follows. We made attention to no angular aberration in the display-type analyzer of Daimon’s configuration, while the principal is definitely different from the Daimon’s one; we realized the spatial-dispersive character depending on the pass energy [4,5]. Fig. 2(a) shows typical trajectories of the electrons entering at five different incident angles. The solid lines represent the trajectories of electrons with energy E0, and the dotted line with 0.9E0, the long dashed line with 1.05E0. Insert in Fig. 2(a) is the magnified trajectories at the aperture point. We confirmed perfect focus of electron beam with energy E0, which means that no angular aberration is realized. The electron beams with different energy from E0 focus at the different point of aperture, but the focus is not perfect; the angular aberration appears. It should be noted that the focus points are different depending on the energy. Namely, the spatial dispersive function is realized, if we limited acceptance angle.
0.1 d = 1.0 mm d = 0.3 mm d = 0.1 mm Experiment
0.09 E/E0
20˚
Energy Resolution
SU
L34
0.08 0.07 0.06
106.9 ~ 146.9 [deg]
0.05 0.04 0.03 0.02 0.01 0 90 100 110 120 130 140 150 160 170 180 Incident Angle α [deg] (b)
Fig. 2. Typical trajectories of electrons with 0.95E0, E0, and 1.05E0 energy, where E0 is the pass energy (a). The angular dependence of resolving power DE/E calculated at aperture diameter of 1, 0.3 and 0.1 mm and the experimental data at the aperture diameter of 1 mm (b).
We also calculated resolving power as a function of the incidence angle a as defined in Fig. 1. The calculated results for three diameters of aperture, 1.0, 0.3, and 0.1 are shown in Fig. 2(b). The point source at S was assumed, because we used focused electron beam as the primary source. The experimental points indicated solid circular are discussed later in this article. Fig. 2(b) shows that the function of the energy analysis disappears at 90 and 180, and that it works well in the wide angle-range around 130. The figure also shows that decrease of aperture diameter decreases DE/E0 and increases acceptance angle-range. In following experiments, we adapted the aperture diameter of 1 mm and the acceptance angle range from 106.6 to 146.6. Our experimental conditions were as follows; the main chamber was evacuated by diffusion pump with N2-liquid cold trap and sublimation pump, and the base pressure was kept blow 2 · 10 8 Pa.
SU N IE SC RS CE E A TT RF LE
3. Experimental results and discussion 3.1. Energy resolution We observed typical electron energy loss spectroscopy (EELS) and AES spectra of a clean Si(1 1 1) surface shown in Fig. 3. The AES peak of Si LVV appears in AES spectrum (a) and an elastic peak and six plasmon-loss peaks are observed in spectrum (b). The full width at half maximum (FWHM) of the elastic peak in the EELS spectrum is 1.66 eV. Fig. 3(c) shows resolving power DE/E0 as a function of the pass energy. The solid line is calculated curve and the filled circles are the experimental data. In this calculation, the energy width (FWHM) of primary beam was assumed to be 500 meV, and was convoluted with the analyzer-specific resolving power. The experimental results fairly agree with the calculated ones. In the energy
range over 30 eV, the experimental data points are situated slightly below the calculated ones, which may be attributed to the fact that effective aperture diameter is smaller than that of the real one owing to the edge-effect: the thickness of the aperture or the carbon-coatings. As a result, DE/ E0 is lower than the expected one. The experimental data are reproduced well by using aperture diameter of 0.92 mm. 3.2. Angular resolution To evaluate the performance of the angular distribution of spectra, we observed the low energy electron diffraction (LEED) pattern of clean Si(1 1 1)—7 · 7 surface prepared by flash-heating. As shown in Fig. 4(a), the mesh structure of pre-retard optics is clearly observed in the LEED pattern. The shadow of the rectangular shape of the mesh is
Resolving Power E/E0
Intensity [a.u.]
0.1
87eV LVV
L35
Calculation Experimental Data
0.08
0.06
0.04
0.02
60
80
100
120
140
160
1
20
40
60
80
100
Pass Energy [eV]
Electron Energy [eV] (a)
10
0
(c)
2 3 4
5 6
Intensity [a.u.]
7
~10 5
0
0
100 Loss Energy [eV] (b)
Fig. 3. AES (a) and EELS (b) spectra of Si(1 1 1). The energy of the primary beam is 1.5 kV beam voltage. The sample current is 1 nA beam current. The pass energy is 100 eV. Resolving power DE/E0 as a function of the pass energy (c).
CE
D. Sakai et al. / Surface Science 600 (2006) L33–L37
CE RF A LE CE TT S ER CIE S N
SU
L36
D. Sakai et al. / Surface Science 600 (2006) L33–L37
Fig. 4. LEED pattern of Si(1 1 1) 7 · 7 structure (a) and intensity profile in the vertical (upper) and horizontal axes (lower) on the LEED pattern (b). The energy of primary beam is 209 eV.
not distorted, which indicates good preservation of angular information. By using size of the (0 0) spot in this LEED pattern, we evaluate the angular resolution of the spectra. Fig. 4(b) shows the intensity distributions both in vertical and horizontal axes. The FWHM of the (0 0) diffraction spot along the axes are 0.50 and 0.33, respectively. Considering the shadowing effect of the mesh, we conclude that the angular resolution is less than 0.50.
we obtained the resolving power DE/E as a function of incident angle a indicated in Fig. 1. The angular dependence of the resolving power is shown in Fig. 2(c). Although the aperture diameter was 1 mm, the experimental results agree with the calculated ones for aperture diameter 0.92 mm. The difference is attributed to edge-effect of decreasing the effective aperture diameter. 3.4. Angular resolved spectra
3.3. Energy resolution as a function of incident angle To evaluate the dependence of energy resolution on incident angle, we measured the energy width (FWHM) of the elastic peak of specular beam by changing the incident direction to crystal surface. Deconvoluting the peak with the energy width of primary electron beam 500 meV,
One of the features of this analyzer is to allow the angleresolved energy analysis. To demonstrate it, we measured the intensities of CCD images at the 17 different areas between (0 0) and (0 1) diffraction spots of the LEED pattern in Fig. 5(a), and made the angle-resolved energy loss spectra of ZrB2 (0 0 0 1) as shown in Fig. 5(b). All spectra are
Fig. 5. A LEED pattern of a clean ZrB2 (0 0 0 1) surface (a) and angle-resolved EELS spectra at 17 different directions between two directions of the (1 0) and (1 1) diffraction spots (b). The energy of primary beam is 250 eV, the pass energy is 100 eV.
SU N IE SC RS CE E A TT RF LE
normalized to the intensities of the elastic peaks, respectively. Three kinds of peaks are found in the spectra, at the loss energies of 17.5 eV, 22 eV, and 43 eV. They correspond to the surface-plasmon loss (PS), the bulk-plasmon loss (PB), and the double bulk-plasmon loss (PDB) of this material, respectively. The differences of the peak-heights on surface-plasmon loss (PS) are found. This fact shows that this analyzer works well for angle-resolved energy analysis. 4. Conclusion We modified the display type analyzer proposed by Daimon et al., and realized spatial-dispersion type analyzer by limiting the acceptance angle. It woks well as a spatial dispersive analyzer, which provides high energy-resolved spectra. We evaluated angular resolution, energy resolution of
L37
this analyzer on the basis of the data of AES, EELS, and LEED. The analyzer performed well as the theoretical estimations expected. The capability of angle-resolved analysis was also confirmed to be effective. These features show that the analyzer is applicable to experiments of angle-resolved ultraviolet photoelectron spectroscopy. References [1] K. Siegbahn et al., ESCA-Atomic Molecular and Solid State Structure Studied by Means of Electron Spectroscopy, Almquist & Wiksells, Upssala, 1967. [2] P.W. Palmberg, G.K. Bohn, J.C. Tracy, J. Appl. Phys. Lett. 15 (1969) 254. [3] H. Daimon, Rev. Sci. Instrum. 59 (1988) 545. [4] H. Daimon, Shozo Ino, Rev. Sci. Instrum. 61 (1990) 57. [5] H. Daimon, J. Electron. Spectrosc. Relat. Phenom. 24 (2002) 139. [6] D.E. Eastman, J.J. Donelon, N.C. Hien, F.J.Hi. Daimon, Nucl. Instrum. Methods Phys. Res. 172 (1980) 327.
CE
D. Sakai et al. / Surface Science 600 (2006) L33–L37
Surface Science Letters
Construction of an electron analyzer with a wide acceptance solid angle Daisuke Sakai a,*, Daisuke Miura a, Takeshi Nakajima a, Tsuyoshi Ishikawa a, Chuhei Oshima a, Hideo Iwai b, Yoshimasa Nihei c a
Institute of Material Science and Technology, Waseda University, 2-8-16 Nishiwaseda, Shinjuku-ku, Tokyo 169-0051, Japan b ULVAC-PHI, Inc., 370 Enzo, Chigasaki-shi, Kanagawa 253-0084, Japan c Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-8510, Japan Received 4 September 2005; accepted for publication 21 November 2005 Available online 27 December 2005
Abstract We have developed a new electron energy analyzer with a large solid angle of 0.14p, which is comparable to that of cylindrical mirror analyzer. Typical energy resolution was DE/E0 0.016 for the aperture of 1 mm and central radius of 100 mm, and typical angular resolution was less than 0.5. 2005 Elsevier B.V. All rights reserved. Keywords: Auger electron spectroscopy (AES); Electron energy loss spectroscopy (EELS); Electron spectroscopy; Low energy electron diffraction (LEED)
1. Introduction Electron energy analyzers are used for surface analysis. For X-ray photoelectron spectroscopy, concentric hemispherical analyzer (CHA) is widely used, and Auger electron spectroscopy (AES) employs cylindrical mirror analyzer (CMA) because of high signal intensity [1,2]. Some of CHA also have a function of angle-resolved measurement, although the measurement is time-consuming. In contrast, CMA is not suitable for angle-resolved measurement, because electrons entering with definite pass energy in the directions around 42 from the central axis are integrally detected and it makes difficulty of angle-resolved measurements in any directions. An electron energy analyzer, equipped with both wide acceptance angle such as that of CMA and angle-resolved measuring such as that of CHA, has been desired. Daimon et al. constructed a display-type analyzer, the features of which are no angular aberration in the ideal electric field case, 2p sr solid angle, and capability of angle-resolved analysis [3]. However, this analyzer had *
Corresponding author. E-mail address: [email protected] (D. Sakai).
0039-6028/$ - see front matter 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.susc.2005.11.028
weakness. Namely, the energy resolution depends on incident directions, and in the certain directions the function disappears [4]. Hence, additional electrodes had to be inevitably installed for function of low and high energy pass filters [5]. As a result, the principle of the energy analyzer’s was the same as that of a display-type analyzer developed by Eastman et al. [6]. In this work, we limited the acceptance angle of the display type analyzer, and realized the spatial-dispersive type analyzer, which works in such a way as CHA and CMA. The structure of our spectrometer is simple. The acceptance solid angle is comparable to that of CMA, being three orders of magnitude wider than that of conventional CHA. This can shorten the measurement time down to less than a thousandth of that of conventional CHA. In this paper, we report the trajectory calculations, the structure and the design, and the experimental results for evaluating the performance. 2. System configuration A schematic diagram of the analyzer constructed in this work is shown in Fig. 1. It consists of pre-retard optics, spherical deflector, and a screen with MCP. The pre-retard
CE RF A LE CE TT S ER CIE S N
D. Sakai et al. / Surface Science 600 (2006) L33–L37 Outer spherical electrode
E/E0 = 0.95 E/E0 = 1.00 E/E0 = 1.05
Aperture A 20˚
20˚
O
Three guard rings MCP Screen
20˚
α S
Pre–retard optics Electron gun
Specimen
(a)
Inner spherical electrode
Fig. 1. A schematic diagram of the analyzer constructed in this work. The point S is the specimen, the point A is the aperture, and the point O is the middle point of the line AS as OS = OA = 50 mm. The angle a is incidence angle. The thick curve is a trajectory of an electron emitted from the point S with proper energy.
optics is made up of two concentric spherical-shaped meshes. Transmission of electrons through each mesh is 88%, and high transmission of 88% through these two meshes was established, because the hole-positions of both the meshes are aligned. The pre-retard optics forms retarding field between the two meshes as high-pass filter, and improves the energy resolution by reducing the pass energy of incoming electrons. The spherical deflector consists of concentric spherical outer and inner electrodes with 60 mm and 120 mm radii, guard rings and an aperture of 1 mm diameter. Electrons entering to the spherical deflector pass through spherical-shaped meshes on the inner electrode. The point O in Fig. 1 is the middle point of the line AS as OS = OA = 50 mm, and it is also a center of equi-potential lines (1/r) generated between the inner and outer electrodes. We installed an electron gun with ZrO/W source together with electro-static lens manufactured by APCO Inc.; the spatial resolution of SEM image was 50 nm. The working principal of the analyzer is as follows. We made attention to no angular aberration in the display-type analyzer of Daimon’s configuration, while the principal is definitely different from the Daimon’s one; we realized the spatial-dispersive character depending on the pass energy [4,5]. Fig. 2(a) shows typical trajectories of the electrons entering at five different incident angles. The solid lines represent the trajectories of electrons with energy E0, and the dotted line with 0.9E0, the long dashed line with 1.05E0. Insert in Fig. 2(a) is the magnified trajectories at the aperture point. We confirmed perfect focus of electron beam with energy E0, which means that no angular aberration is realized. The electron beams with different energy from E0 focus at the different point of aperture, but the focus is not perfect; the angular aberration appears. It should be noted that the focus points are different depending on the energy. Namely, the spatial dispersive function is realized, if we limited acceptance angle.
0.1 d = 1.0 mm d = 0.3 mm d = 0.1 mm Experiment
0.09 E/E0
20˚
Energy Resolution
SU
L34
0.08 0.07 0.06
106.9 ~ 146.9 [deg]
0.05 0.04 0.03 0.02 0.01 0 90 100 110 120 130 140 150 160 170 180 Incident Angle α [deg] (b)
Fig. 2. Typical trajectories of electrons with 0.95E0, E0, and 1.05E0 energy, where E0 is the pass energy (a). The angular dependence of resolving power DE/E calculated at aperture diameter of 1, 0.3 and 0.1 mm and the experimental data at the aperture diameter of 1 mm (b).
We also calculated resolving power as a function of the incidence angle a as defined in Fig. 1. The calculated results for three diameters of aperture, 1.0, 0.3, and 0.1 are shown in Fig. 2(b). The point source at S was assumed, because we used focused electron beam as the primary source. The experimental points indicated solid circular are discussed later in this article. Fig. 2(b) shows that the function of the energy analysis disappears at 90 and 180, and that it works well in the wide angle-range around 130. The figure also shows that decrease of aperture diameter decreases DE/E0 and increases acceptance angle-range. In following experiments, we adapted the aperture diameter of 1 mm and the acceptance angle range from 106.6 to 146.6. Our experimental conditions were as follows; the main chamber was evacuated by diffusion pump with N2-liquid cold trap and sublimation pump, and the base pressure was kept blow 2 · 10 8 Pa.
SU N IE SC RS CE E A TT RF LE
3. Experimental results and discussion 3.1. Energy resolution We observed typical electron energy loss spectroscopy (EELS) and AES spectra of a clean Si(1 1 1) surface shown in Fig. 3. The AES peak of Si LVV appears in AES spectrum (a) and an elastic peak and six plasmon-loss peaks are observed in spectrum (b). The full width at half maximum (FWHM) of the elastic peak in the EELS spectrum is 1.66 eV. Fig. 3(c) shows resolving power DE/E0 as a function of the pass energy. The solid line is calculated curve and the filled circles are the experimental data. In this calculation, the energy width (FWHM) of primary beam was assumed to be 500 meV, and was convoluted with the analyzer-specific resolving power. The experimental results fairly agree with the calculated ones. In the energy
range over 30 eV, the experimental data points are situated slightly below the calculated ones, which may be attributed to the fact that effective aperture diameter is smaller than that of the real one owing to the edge-effect: the thickness of the aperture or the carbon-coatings. As a result, DE/ E0 is lower than the expected one. The experimental data are reproduced well by using aperture diameter of 0.92 mm. 3.2. Angular resolution To evaluate the performance of the angular distribution of spectra, we observed the low energy electron diffraction (LEED) pattern of clean Si(1 1 1)—7 · 7 surface prepared by flash-heating. As shown in Fig. 4(a), the mesh structure of pre-retard optics is clearly observed in the LEED pattern. The shadow of the rectangular shape of the mesh is
Resolving Power E/E0
Intensity [a.u.]
0.1
87eV LVV
L35
Calculation Experimental Data
0.08
0.06
0.04
0.02
60
80
100
120
140
160
1
20
40
60
80
100
Pass Energy [eV]
Electron Energy [eV] (a)
10
0
(c)
2 3 4
5 6
Intensity [a.u.]
7
~10 5
0
0
100 Loss Energy [eV] (b)
Fig. 3. AES (a) and EELS (b) spectra of Si(1 1 1). The energy of the primary beam is 1.5 kV beam voltage. The sample current is 1 nA beam current. The pass energy is 100 eV. Resolving power DE/E0 as a function of the pass energy (c).
CE
D. Sakai et al. / Surface Science 600 (2006) L33–L37
CE RF A LE CE TT S ER CIE S N
SU
L36
D. Sakai et al. / Surface Science 600 (2006) L33–L37
Fig. 4. LEED pattern of Si(1 1 1) 7 · 7 structure (a) and intensity profile in the vertical (upper) and horizontal axes (lower) on the LEED pattern (b). The energy of primary beam is 209 eV.
not distorted, which indicates good preservation of angular information. By using size of the (0 0) spot in this LEED pattern, we evaluate the angular resolution of the spectra. Fig. 4(b) shows the intensity distributions both in vertical and horizontal axes. The FWHM of the (0 0) diffraction spot along the axes are 0.50 and 0.33, respectively. Considering the shadowing effect of the mesh, we conclude that the angular resolution is less than 0.50.
we obtained the resolving power DE/E as a function of incident angle a indicated in Fig. 1. The angular dependence of the resolving power is shown in Fig. 2(c). Although the aperture diameter was 1 mm, the experimental results agree with the calculated ones for aperture diameter 0.92 mm. The difference is attributed to edge-effect of decreasing the effective aperture diameter. 3.4. Angular resolved spectra
3.3. Energy resolution as a function of incident angle To evaluate the dependence of energy resolution on incident angle, we measured the energy width (FWHM) of the elastic peak of specular beam by changing the incident direction to crystal surface. Deconvoluting the peak with the energy width of primary electron beam 500 meV,
One of the features of this analyzer is to allow the angleresolved energy analysis. To demonstrate it, we measured the intensities of CCD images at the 17 different areas between (0 0) and (0 1) diffraction spots of the LEED pattern in Fig. 5(a), and made the angle-resolved energy loss spectra of ZrB2 (0 0 0 1) as shown in Fig. 5(b). All spectra are
Fig. 5. A LEED pattern of a clean ZrB2 (0 0 0 1) surface (a) and angle-resolved EELS spectra at 17 different directions between two directions of the (1 0) and (1 1) diffraction spots (b). The energy of primary beam is 250 eV, the pass energy is 100 eV.
SU N IE SC RS CE E A TT RF LE
normalized to the intensities of the elastic peaks, respectively. Three kinds of peaks are found in the spectra, at the loss energies of 17.5 eV, 22 eV, and 43 eV. They correspond to the surface-plasmon loss (PS), the bulk-plasmon loss (PB), and the double bulk-plasmon loss (PDB) of this material, respectively. The differences of the peak-heights on surface-plasmon loss (PS) are found. This fact shows that this analyzer works well for angle-resolved energy analysis. 4. Conclusion We modified the display type analyzer proposed by Daimon et al., and realized spatial-dispersion type analyzer by limiting the acceptance angle. It woks well as a spatial dispersive analyzer, which provides high energy-resolved spectra. We evaluated angular resolution, energy resolution of
L37
this analyzer on the basis of the data of AES, EELS, and LEED. The analyzer performed well as the theoretical estimations expected. The capability of angle-resolved analysis was also confirmed to be effective. These features show that the analyzer is applicable to experiments of angle-resolved ultraviolet photoelectron spectroscopy. References [1] K. Siegbahn et al., ESCA-Atomic Molecular and Solid State Structure Studied by Means of Electron Spectroscopy, Almquist & Wiksells, Upssala, 1967. [2] P.W. Palmberg, G.K. Bohn, J.C. Tracy, J. Appl. Phys. Lett. 15 (1969) 254. [3] H. Daimon, Rev. Sci. Instrum. 59 (1988) 545. [4] H. Daimon, Shozo Ino, Rev. Sci. Instrum. 61 (1990) 57. [5] H. Daimon, J. Electron. Spectrosc. Relat. Phenom. 24 (2002) 139. [6] D.E. Eastman, J.J. Donelon, N.C. Hien, F.J.Hi. Daimon, Nucl. Instrum. Methods Phys. Res. 172 (1980) 327.
CE
D. Sakai et al. / Surface Science 600 (2006) L33–L37