In vivo evaluation of two forms of urea in the skin by Raman spectroscopy after application of urea-containing cream.BACKGROUND/PURPOSE
 We therefore applied Raman spectroscopy to evaluate the depth profile of urea content in the skin. 
Raman spectroscopy
Raman spectra of the skin were measured at 2-μm intervals from the skin surface toward the interior using a confocal Raman spectrometer (model 3510 SCA) before and 15, 60, and 120 min after the application of the creams. 
confocal Raman spectrometer (model 3510 SCA)