Schematic of Orbitrap mass spectrometer equipped with laser for photodissociation and examples of UVPD mass spectra of the 11+ charge state of (A) ubiquitin and (B) the 20+ charge state of myoglobin. Reproduced from Shaw, J.B., Li, W., Holden, D.D., Zhang, Y., Griep-Raming, J., Fellers, R.T., Early, B.P., Thomas, P.M., Kelleher, N.L., Brodbelt, J.S. J. Am. Chem. Soc., 2013, 135, 12646–12651 (ref 116). Copyright 2013 American Chemical Society.