D’SA, EURICO J., AND ROBERT G. STEWARD Liquid capillary waveguide application in absorbance spectroscopy

742 Commentsquartz/polymer waveguides offers strong advantages in the Referencesmeasurement of CDOM in seawater. The need to carefullymatch the refractive indices of natural and reference solu- D’SA, E. J., R. G. STEWARD,A.V ODACEK,N.V.B LOUGH, AND D.tions (very challenging in estuarine waters) can be mitigated PHINNEY. 1999. Determining optical absorption of colored dis-or eliminated entirely. It is highly desirable to conduct solved organic matter in seawater with a liquid capillary wave-guide. Limnol. Oceanogr. 44: 1142–1148.CDOM measurements using waveguides that do not propa-GREEN,S.A.,AND N. V. BLOUGH. 1994. Optical absorption andgate light across optical interfaces. The best means offluorescence properties of chromophoric dissolved organicachieving this objective is the use of waveguides in whichmatter in natural waters. Limnol. Oceanogr. 39: 1903–1916.the liquid core is in direct physical contact with walls thatSTONE, J. 1972. Optical transmission in liquid-core quartz fibers.have a lower index of refraction than water. Additionally, weAppl. Phys. Lett. 20: 239–240.note that if such an LCW (i.e., n , n ) is itself immersedT WTSUNODA, K., A. NOMURA,J.Y AMADA, AND S. NISHI. 1989. Thein water, any light propagating within the Teflon wall willpossibility of signal enhancement in liquid absorption spec-efficiently exit the LCW. In this case, even for poorly col-trometry with a long capillary cell utilizing successive totallimated light, only light ...