But standard bond-breaking chemical reactions tend to be indiscriminate. This might necessitate first adding 'protecting groups' to prevent the wrong bonds from being broken, and subsequently removing theses groups-extra steps which lead to greater costs and lower yields. One of the techniques that has been explored for selectively breaking bonds is to use laser light to pump energy into just those bonds to be severed, until they shake apart. Different bonds have different resonant frequencies, and so absorb light of different frequencies. Dietrich Menzel, Peter Feulner and colleagues at the Technical University of Munich, Germany, have adopted a very different approach.
Chemical bonds result from the sharing of electrons between atoms.
The researchers figured that they could break bonds by sucking the electrons out of them. They used X-rays to 'burn holes' in the electron shells around certain atoms. Some of the electrons involved in bonding then fell into these holes. X-rays have a higher frequency than visible light, and so carry more energy. This means that, rather than exciting bonds into vibration, X-rays have enough energy to rearrange the innermost electrons around atoms.