BL-20A 3-m normal incidence monochromator

spokesperson:J. Adachi

1. Outline

This beamline covers the lower photon energy range of the vacuum ultraviolet region. Due to a large acceptance angle of bending radiation, a high flux photon is supplied with a relatively high monochromaticity. A schematic of optical system is shown in Fig. 1. Bending radiation is focused with the two pre-mirrors, M1 and M2, onto an entrance slit, S1, dispersed with a 3-m concave diffraction grating, and finally refocused with the M3 and M4 mirrors to the focusing point (FP).

Figure 1 Schematic of the optical system of the 3-m normal incidence monochromator installed at BL-20A.


2. Performance

Optical system : cf. attached figure

Energy region : 5-40 eV ( for a 1200-grooves/mm grating) When a 2400-grooves/mm grating is used, the energy region is 10-40 eV.

Resolution : iE/ΔEj=3~104 @100 nm with a 2400-grooves/mm grating

Beamsize : 3mm(H)~1mm(V)

Flux : 1012photons/sec . Flux with a 1200-grooves/mm grating is shown in Figure 2.

Figure 2 Photon flux obtained with a 1200-grooves/mm grating. The slit widths are 1mm, and the resolution is 2.5 A.


3. Remarks

Atomic and molecular science is one of the main subjects carried out at this beamline, as shown in the followings.

Dissociative photoionization of H2 and D2 in the energy region of 25 - 45 eV, K. Ito, R. I. Hall and M. Ukai, J. Chem. Phys., 104, 8449 (1996)FPhotoionization of argon, krypton and xenon clusters in the inner valence shell region, R. Thissen, P. Labalnquie, R. Hall, M. Ukai and K. Ito, Eur. Phys. J., D4, 335 (1998).

Ground and excited states of Xe2+ observed by high resolution threshold photoelectron spectroscopy of Xe2,Y. Lu, Y. Morioka, T. Matsui, T. Tanaka, H. Yoshii, R. I. Hall, T. Hayaishi and K. Ito, J. Chem. Phys., 102, 1553 (1995)FRotationally resolved ZEKE spectra of the X2Sg+ (v+=0 to 3), B2Su+ (v+=0) and C2Su+ (v+=0) states of N2+, T. Aoto, H. Yoshii, T. Hayaishi and Y. Morioka, Phys. Scr., 65, 139 (2002).

Inner-valence states of O2+and dissociation dynamics studied by threshold photoelectron spectroscopy and configuration interaction calculation, Y. Hikosaka, T. Aoto, R.I. Hall, K. Ito, R. Hirayama, N. Yamamoto and E. Miyoshi, J. Chem. Phys., 119, 7693 (2003).

State-to-state behavior in the neutral dissociation of O2 far beyond the ionization threshold. M. Ukai, S. Machida, K. Kameta, M. Kitajima, N. Kouchi, Y. Hatano and K. Ito, Phys. Rev. Letters, 74, 239 (1995).


4. Miscellaneous

1) This beamline is equipped with a control system, which, beside the monochromator control, enables the users to carry out multi-channel scaling and pulse hight analysis.

2) The experimental station of this beamline is constructed on a mezzanine floor, and experimental apparatus can be lifted up by a crane.

3) There is a constraint for the physical size of the experimental apparatus brought in. Please contact the spokesperson before your application of the machine time.

5. References

1. K. Ito et al., Rev. Sci. Instr., 66, 2119 (1995).
2. T. Hayaishi, PF98 measurements system (in Japanese).

Last modified : 2013-04-18