Growth and characterization of naphthalene single crystals grown by modified vertical Bridgman method

Suthan, T.; Rajesh, N.P.; Dhanaraj, P.V.; Mahadevan, C.

doi:10.1016/j.saa.2009.09.041

Cited by 45 publications

(12 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The fully screened dielectric constants are in excellent agreement with the measured values of ε. 4,18,26,27 For pentacene, ε full is also close to the values of 3.2 and 3.6, obtained by Sharifzadeh et al 3 from GW calculations within the random phase approximation (RPA). Indeed, the SCS method solves the RPA equation for a collection of QHOs in the dipole approximation.…”

supporting

confidence: 84%

Electrodynamic response and stability of molecular crystals

Schatschneider

Liang²,

Reilly

et al. 2013

Phys. Rev. B

View full text Add to dashboard Cite

We show that electrodynamic dipolar interactions, responsible for long-range fluctuations in matter, play a significant role in the stability of molecular crystals. Density functional theory calculations with van der Waals interactions determined from a semilocal "atom-in-a-molecule" model result in a large overestimation of the dielectric constants and sublimation enthalpies for polyacene crystals from naphthalene to pentacene, whereas an accurate treatment of nonlocal electrodynamic response leads to an agreement with the measured values for both quantities. Our findings suggest that collective response effects play a substantial role not only for optical excitations, but also for cohesive properties of noncovalently bound molecular crystals. Polyacene molecular crystals form a fundamental class of aromatic solids, and have been extensively studied as potential materials for organic electronics. [1][2][3] It is understood that the optical properties of polyacenes are very sensitive to longrange intra-and intermolecular electrodynamic interactions. This is reflected by shifts in the optical absorption frequencies upon increasing the molecule size or upon solid formation, 4 and is further exhibited by the visible color of oligoacene crystals, which changes from transparent in naphthalene and anthracene, to bright orange in tetracene, and deep blue in pentacene. 4,5 The optical absorption spectrum is directly related to the polarizability through the Kramers-Kronig transformation.6 Therefore, the observed changes in the optical spectrum upon crystallization of polyacenes are accompanied by a change in the molecular polarizability. In addition, these changes in polarization should directly impact the crystal lattice energy. However, the effect of electrodynamic intermolecular interactions on the cohesive properties of molecular crystals remains poorly understood. In this Rapid Communication, we show that the dipolar electrodynamic coupling between polyacene molecules reduces the solid dielectric constant by 15%, and has an impact of up to 0.5 eV per molecule on the computed van der Waals (vdW) energies and sublimation enthalpies of these molecular crystals. Our results imply that electrodynamic response is crucial for describing both the cohesive energy and the optical properties of molecular crystals, also providing strong quantitative support to empirical relations between stability and refractive index of molecular crystals. 7Polyacene crystals are extended aromatic networks characterized by polarizable π clouds. Therefore, an appreciable part of the crystal lattice energy stems from ubiquitous attractive vdW dispersion interactions. When studying the cohesion of molecular systems, for example, using densityfunctional theory (DFT) 8,9 or classical potentials, 10 the vdW energy is typically computed using effective polarizabilities for hybridized "atoms" inside a molecule. It is common to approximate the frequency-dependent polarizability of every atom using a single effective excitation frequency (also called t...

show abstract

supporting

confidence: 84%

Electrodynamic response and stability of molecular crystals

Schatschneider

Liang²,

Reilly

et al. 2013

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…Air capacitance (C air ) was also measured. The dielectric constant and AC conductivity were calculated [6]. The temperature dependence of the dielectric constant (e r ), dielectric loss (tan d) and AC conductivity (s ac ) at different frequencies are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The furnace construction was discussed in our previous paper [6]. Mostly ampoules that are conical in shape obtain good crystal; in fact the conical tip in the ampoule is the point of initiation of the solidification and controls further growth.…”

Section: Crystal Growthmentioning

confidence: 99%

“…Mostly ampoules that are conical in shape obtain good crystal; in fact the conical tip in the ampoule is the point of initiation of the solidification and controls further growth. In ampoule as the cone length increases the crystal quality increases [6] and the ampoule of the prescribed cone angle was found to be the most optimum to obtain inclusion-free good quality transparent crystals [9][10][11]. In the present study we use the single wall ampoule made of borosil glass; it is 26 cm high with 1.5 cm diameter in the heel part.…”

Section: Crystal Growthmentioning

confidence: 99%

“…In the Bridgman growth the solid-liquid interface shape is a key factor to determine the quality of growth. In the Bridgman technique, many different shapes of ampoules were developed to grow crystals [6][7][8]. The single wall ampoule with conical tip is very useful to grow good quality transparent crystals.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations