Chapter 4
X-ray Optics and Synchrotron Beamlines
4.1 Introduction
Storage rings and their associated insertion devices are wonderful sources of synchrotron radiation, but the X-rays are not useful unless they are brought to bear on a
sample in an experiment. This generally involves transporting the X-rays out of the
storage ring, selecting a part of the spectrum, and perhaps focusing it on the sample.
All of this is the job of a beamline using X-ray optics. At first glance, X-ray
beamlines can appear dauntingly complex and very different from UV-visible
instruments (Fig. 4.1). However, on closer inspection, one finds mostly the same
components as on a desktop grating spectrometer—slits, mirrors, and gratings
(or crystals). In this chapter, we will discuss what makes X-ray optics look so
different from more familiar components used in UV-visible and IR spectroscopies.
Why should we care about X-ray optics? As a fundamental part of your synchrotron spectroscopy experiment, some of the optics will be directly under your control.
For example, you might be required to:
• Choose optimum crystals or gratings for your energy range.
• Move and bend mirrors to position and focus the beam.
• Move crystals or gratings to change photon energy.
• Adjust slits for appropriate energy resolution.
Although computer control might allow you to do all of these things without too
much thinking, you will get better results if your understanding of X-ray optics gets
to a deeper level than mere “knob knowledge.” Understanding the optics will allow
you to get more flux and a higher-quality beam—leading to a faster and better
measurement.
There is no new physics in X-ray optics—the same phenomena of refraction,
reflection, and diffraction occur at all frequencies, and the same general equations
apply from the infrared regime to γ-rays. However, the parameters that govern the
© Springer Nature Switzerland AG 2020
S. P. Cramer, X-Ray Spectroscopy with Synchrotron Radiation, Biological and Medical
Physics, Biomedical Engineering, https://doi.org/10.1007/978-3-030-28551-7_4
69
X-ray Optics and Synchrotron Beamlines
4.1 Introduction
Storage rings and their associated insertion devices are wonderful sources of synchrotron radiation, but the X-rays are not useful unless they are brought to bear on a
sample in an experiment. This generally involves transporting the X-rays out of the
storage ring, selecting a part of the spectrum, and perhaps focusing it on the sample.
All of this is the job of a beamline using X-ray optics. At first glance, X-ray
beamlines can appear dauntingly complex and very different from UV-visible
instruments (Fig. 4.1). However, on closer inspection, one finds mostly the same
components as on a desktop grating spectrometer—slits, mirrors, and gratings
(or crystals). In this chapter, we will discuss what makes X-ray optics look so
different from more familiar components used in UV-visible and IR spectroscopies.
Why should we care about X-ray optics? As a fundamental part of your synchrotron spectroscopy experiment, some of the optics will be directly under your control.
For example, you might be required to:
• Choose optimum crystals or gratings for your energy range.
• Move and bend mirrors to position and focus the beam.
• Move crystals or gratings to change photon energy.
• Adjust slits for appropriate energy resolution.
Although computer control might allow you to do all of these things without too
much thinking, you will get better results if your understanding of X-ray optics gets
to a deeper level than mere “knob knowledge.” Understanding the optics will allow
you to get more flux and a higher-quality beam—leading to a faster and better
measurement.
There is no new physics in X-ray optics—the same phenomena of refraction,
reflection, and diffraction occur at all frequencies, and the same general equations
apply from the infrared regime to γ-rays. However, the parameters that govern the
© Springer Nature Switzerland AG 2020
S. P. Cramer, X-Ray Spectroscopy with Synchrotron Radiation, Biological and Medical
Physics, Biomedical Engineering, https://doi.org/10.1007/978-3-030-28551-7_4
69