Raw materials : Aspirin, Acetaminophen, Ibuprofen(>99%)Solvent : Ethanol, Acetone(>99.5%)

Crystal Growth method : Slow evaporation

Aspirin – C9H8O4

symmetry : monoclinicspace group : P21/cmelting point : 135℃

Acetaminophen – C8H9NO2

symmetry : monoclinicmelting point : 167℃

Ibuprofen – C13H18O2

symmetry : monoclinicmelting point : 78℃

Probe acoustic branch near the Brillouin zone center

sound velocity, elastic constant

KIM Tae Hyun , KO Jae-Hyeon, LEE Kwang-Sei1, KOJIMA Seiji2

Hallym University, Department of Physics. 1Inje University, Department of Nano Systems Engineering. 2University of Tsukuba, Institute of Materials Science.*Corresponding Author: hwangko@hallym.ac.kr

Characterization of exact elastic property of crystalline phases of pharmaceuticals is very important. It provide fundamental material constants related to the intermolecular potential and is essential for the engineering design of drug materials. However, there have been only few studies on the exact elastic properties of pharmaceuticals. So, Single crystals of pharmaceutical materials were obtained by slow evaporation . Using Brillouin light scattering, we did study elastic properties of representative pharmaceutical single crystals.

*This research was supported by Science Research Program Through the National Research Foundation of Korea(NRF) funded by the Ministry of Education, Science and Technology(2009-0066894).

Microscope

532nm DPSS laser

PM

Power

Supply

Control

Box

Gh

ost

sample

Excitation Source : Diode-pumped Solid state laser(single mode, 532nm)

Cryostat Cell : Linkham(THMS 600)

Sandercock type tandem Fabry-Perot Interferometer+ Microscope(Olympus BX41)

Micro-Brillouin Scattering

Back scattering geometry(180˚)Free spectral range : 30GHz ↓Temperature range : 88K ~ melting point

1st Brillouin Zone

Aspirin Acetaminophen Ibuprofen

Raw materials

Mixing

Solvent

The Brillouin spectra of pharmaceutical single crystals(Aspirin, Ibuprofen, Acetaminophen) were measured in a wide temperature range from 87K up to their melting point.

The backscattered Brillouin spectrum of crystals from the dominant plane consists of three Brillouin doublets arising from one longitudinal acoustic (LA) mode and two transverse acoustic (TA) modes.

LA modes exhibited monotonically decreasing behaviors upon heating.

No signs of any structural phase transition at temperatures between 87K and the melting point were observed.

The temperature dependence of the Brillouin frequency shift of the longitudinal acoustic mode was analyzed based on Debye and Einstein lattice models.

T

D

D

DD

D

B

D

dxx

xTTF

TFbT

/

0

34

0

1)exp(3)/(

)/(1)(

1)/exp(

`1)( 0

T

aT

E

E

B

The temperature dependence of the Brillouin frequency shift of the LA mode could be explained by the normal anharmonic lattice theory based on both the Einstein and the Debye models. The above results indicate that the LA modes of three representative pharmaceutical single crystals are affected by the usual lattice anharmonicity.