What is the fine-grained topic of the following text: Researchers usually probe mechanochemical reactions by sampling the reaction mixture at predesignated intervals, however these scientists used their own in situ Raman spectroscopy technique, pioneered in 2014, along with synchrotron x-ray diffraction to monitor the reaction. Only return the topic.
Monitoring mechanochemical reactions using in situ Raman spectroscopy and synchrotron x-ray diffraction