Scientific research glossary of terms
The X-ray diffraction explanation says X-rays are 'refracted'; the technique depends on diffraction. No question tests this wording.
The check-ins use the correct version. The video is Khan Academy's, unchanged.About this video
This British Museum glossary introduces five scientific techniques used to find out what objects are made of, where they come from and how they were made: gas chromatography mass spectrometry, radiography, scanning electron microscopy, X-ray diffraction and X-ray fluorescence spectrometry.
You'll be able to
- match each scientific technique to what it is used to find out.
- explain why non-destructive methods like radiography and portable XRF are useful for museum objects.
Key words
- gas chromatography mass spectrometry (GC-MS)
- A technique that separates a tiny sample in a heated column and identifies resins, fats and waxes.
- radiography
- Using X-rays to see inside an object without opening or damaging it.
- scanning electron microscopy (SEM)
- Scanning a beam of electrons over a surface to see details thousands of times magnified.
- X-ray diffraction (XRD)
- Bouncing X-rays inside a tiny sample to identify materials with a crystal structure, like minerals or corrosion.
- X-ray fluorescence (XRF)
- Firing X-rays at an object so atoms give off a 'fingerprint' that identifies chemical elements.
Transcript
Many of the objects we see in galleries undergo conservation and scientific examination. Here is a glossary of terms the British Museum's conservators and scientists use behind the scenes. Episode one: Scientific research. The British Museum has a department with a team dedicated to scientific research. Their task is to find out what objects are made of where they're from and where and how th ey were constructed.
Gas chromatography mass spectrometry is used to identify resins fats and waxes. A minute sample is dissolved and injected into the chromatograph which is an oven containing a polymer coated column. The samples move through a stream of helium gas and emerge into a detector which produces a chromatogram. The detector here is a mass spectrometer which splits the chemical compounds into ions recorded as a mass spectrum to identify mixtures of materials. For example beeswax and pine resin.
Radiography uses x-rays a special type of invisible light which can pass all the way through objects. By using x-rays we can look inside valuable and delicate objects without opening or damaging them, so we can answer questions about their condition, how they were made, or if anything is hidden inside.
Scanning electron microscopy is used to study objects at magnifications up to several thousand times which is much higher than with light microscopes. The object is viewed by scanning a beam of electrons onto the surface and collecting the signals. These are used to produce a clear image which appears in shades of grey for surfaces as small as one nanometer.
X-ray diffraction is used to identify material with a crystal structure such as stone or minerals. It can also be used to identify corrosion. X-rays are fired into an extremely small sample, bounce inside it, then reflects out and are analysed. The speed and the angle at which X rays are bounced back or refracted helps to tell us the object's composition.
X-ray fluorescence spectrometry or XRF identifies the chemical elements in objects. X-rays are fired into a sample causing atoms to emit fluorescent x-rays which work as a fingerprint for the elements. Portable XRF can be used in situ for objects that can't be brought into the laboratories, or to detect original pigment on objects in galleries before any conservation procedures are carried out. Scientists at the Museum use many other research techniques listed in the Science and Conservation glossary you can find out more by visiting The British Museum website.
To understand more about work at the museum visit: www.britishmuseum.org
Video © Khan Academy, used under CC BY-NC-SA. Watch on Khan Academy. Puzzicle is not affiliated with Khan Academy.