We have used Brillouin scattering to determine the speed of sound in (and hence longitudinal modulus of) A‐ and B‐DNA fibers. The speed of sound is very sensitive to the degree of hydration of the fibers, and measurements have to be made at laser powers below 5 mW to avoid local heating and dehydration. Under those conditions, we obtain sound speed perpendicular to the fiber axis of about 2.2 and 1.9 km/s in A‐ and B‐DNA fibers, respectively. A‐DNA fibers show a small anisotropy with sound speeds along the fiber axis higher by up to 10% B‐DNA fibers appear to be isotropic.
ASJC Scopus subject areas
- Organic Chemistry