Glasslike ultrasonic properties of Dominican amber above helium temperatures

Abstract

Measurements of the ultrasonic attenuation and relative velocity changes of longitudinal waves of frequencies between 5 and 25 MHz are reported for clear yellow Dominican amber at low temperatures. Between 4 and 130 K the attenuation and velocity change are glasslike in their temperature and frequency dependencies. At higher temperatures both properties seemed to be affected by the α or β viscoelastic relaxations. Similar ultrasonic behavior is reported for commercial polymethylmethacrylate. Our results at low temperatures compare well quantitatively with data of other organic and inorganic glasses, except for the stronger logarithmic frequency-dependent velocity change which is observed for both materials.

Phonon attenuation in amorphous solids studied by picosecond ultrasonics

“…The above value of ␤(T) is in good agreement with the value found for PMMA at Brillouin frequencies. 49 Higher precision experiments 50 at MHz frequencies find a similar value of ␤(T) for temperatures down to 120 K. Below this temperature there is a rather sudden drop in ␤ to a value of Ϫ2.8ϫ10 Ϫ5 K Ϫ1 , and ␤ remains almost constant at this value down to 4 K. 50 Another abrupt change in the value of ␤(T) is observed 51 for PMMA at the glass transition temperature, T g Ӎ380 K. We will return in Sec. IV B to discuss the temperature dependence of the sound velocity in glasses in relation to the fracton model.…”

Origin of the blue fluorescence in Dominican amber

“…The data for blue amber, including fluorescence lifetime, allow the identification of perylene as the compound responsible for its distinctive showy fluorescence. 8 Amber-bearing deposits are found in many areas; some of the richest are located in the Dominican Republic. The material is the result of fossilization, over tens of millions years, of resins from specific plants.…”