(IMAGE) Yokohama National University Caption By exciting the transitional metal dichalcogenide monolayers — atomically thin semiconductors — with ultrashort pump pulses, atoms can coherently vibrate and modulate optical responses. The probe pulses can detect the ultrafast modulation that shows peculiar high-frequency overtones of K-point acoustic phonons. Credit Yokohama National University Usage Restrictions News organizations may use or redistribute this image, with proper attribution, as part of news coverage of this paper only. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.