Erratum: Fluorescence transient and optical free induction decay spectroscopy of pentacene in mixed crystals at 2 K. Determination of intersystem crossing and internal conversion rates [J. Chem. Phys. 70, 5807 (1979)]

Vries, Harmen de; Wiersma, Douwe A.

doi:10.1063/1.438845

Cited by 45 publications

(72 citation statements)

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“…M TCþ , via decreasing concen tration), the size of this jump diverges. Our model predicts that the This result of our rigorous theory complements the simple geometric diffuse cone argument of de Vries [14], which is shown in Figure 6. The conventional, but oversimplified, relationship between layer contraction and tilt angle, D d ¼ (1 � cos(h)), is obtained geometri cally by assuming a liquid crystal with perfect orientational order, as shown in Figure 6(a).…”

supporting

confidence: 53%

de Vries Behavior in Smectics near a Biaxiality Induced Smectic A – Smectic C Tricritical Point

Saunders

2009

Molecular Crystals and Liquid Crystals

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We show that a generalized Landau theory for the smectic A and C phases exhibits a biaxiality induced AC tricritical point. Proximity to this tricritical point depends on the degree of orientational order in the system; for sufficiently large orientational order the AC transition is 3D XY like, while for sufficiently small orientational order, it is either tricritical or 1st order. We investigate each of the three types of AC transitions near tricriticality and show that for each type of transition, small orientational order implies de Vries behavior in the layer spacing, an unusually small layer contraction. This result is consistent with, and can be understood in terms of, the ''diffuse cone'' model of de Vries. Additionally, we show that birefrin gence grows upon entry to the C phase. For a continuous transition, this growth is more rapid the closer the transition is to tricriticality. Our model also predicts the possibility of a nonmontonic temperature dependence of birefringence.

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confidence: 53%

de Vries Behavior in Smectics near a Biaxiality Induced Smectic A – Smectic C Tricritical Point

Saunders

2009

Molecular Crystals and Liquid Crystals

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“…When embedded in p-terphenyl at liquid-helium temperatures, the O 3 and O 4 sites have rates exceeding those of the O 1 and O 2 sites by two orders of magnitude. 12,13 When increasing the temperature, the O 1 and O 2 ISC rates were observed to converge to those of O 3 and O 4 . 13,14 For pentacene in benzoic acid at 1.6 K, the ISC was shown to be dominated by a near-resonance of the first excited singlet state S 1 and a vibrational level of a higher triplet state.…”

Section: Introductionmentioning

confidence: 99%

Single-molecule fluorescence autocorrelation experiments on pentacene: The dependence of intersystem crossing on isotopic composition

Brouwer

Köhler

Oijen

et al. 1999

The Journal of Chemical Physics

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Single pentacene molecules containing 13 C or 1 H in a pentacene-d 14 doped p-terphenyl crystal have been studied by fluorescence autocorrelation. The triplet dynamics has been analyzed and a systematic dependence of the S 1 →T 1 intersystem crossing rate on isotopic composition was found. This variation is discussed in terms of a modulation of the near resonance of the first excited singlet state S 1 and vibrational levels of an intermediating triplet state T 3 which results from the distinct isotope dependence of the zero-point energy of both electronic states.

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“…Normally, the layers contract below the transition from SmA* -where θ ≡ 0 in absence of fields -to SmC* or one of its AFLC variations. In some compounds this shrinkage is much smaller than expected, a behaviour which was explained by the Dutch-American crystallographer Adriaan de Vries. He recognised that one must take into account that the molecules have a non-zero average inclination θ mol away from k even if θ = 0, as in SmA*, a result of the orientational disorder characteristic of any LC phase [16][17][18][19]. The uniaxial symmetry around k and the absence of director tilt are consequences of the fact that all directions of molecule inclination are equally probable in the orientational fluctuations.…”

Section: Introductionmentioning

confidence: 99%

The peculiar optic, dielectric and X‐ray diffraction properties of a fluorinated de Vries asymmetric diffuse cone‐model ferroelectric liquid crystal

et al. 2006

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A newly synthesised semi-fluorinated chiral smectic liquid crystal, W504, is investigated by electrooptic, dielectric and x-ray scattering experiments. It exhibits a huge dielectric soft mode response, strong electroclinic effect and a birefringence which increases considerably with the director tilt angle θ, typical characteristics of a SmA*-SmC* transition following the de Vries asymmetric diffuse cone (ADC) model in which the non-zero director tilt in SmC* arises through an ordering of tilting directions rather than an actual increase in average molecule tilt θ mol . In W504 a small increase in θ mol of about 4 • is however detected in the SmC* phase. Although the increase in molecule inclination is much less than the increase in director tilt θ, saturating close to 30 • , it leads to a shrinkage of the smectic layers by about 1Å, a result of the large initial molecule tilt in SmA* , θ mol SmA * ≈ 30 • . The tilting transition in W504 is thus mainly an ADC model disorder-order transition, but it also has a component of a structural transition. The semi-fluorinated molecular structure of W504 leads to a very weak electron density modulation along the layer normal, giving a vanishing form factor in bulk samples which exhibit no (001) x-ray scattering peak. In thin films the (001) peak is however observed, indicating that the electron density modulation is enhanced by the breaking of the head-tail symmetry of the liquid crystal phase at the LC-air interface.2

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Erratum: Fluorescence transient and optical free induction decay spectroscopy of pentacene in mixed crystals at 2 K. Determination of intersystem crossing and internal conversion rates [J. Chem. Phys. 70, 5807 (1979)]

Cited by 45 publications

References 0 publications

de Vries Behavior in Smectics near a Biaxiality Induced Smectic A – Smectic C Tricritical Point

de Vries Behavior in Smectics near a Biaxiality Induced Smectic A – Smectic C Tricritical Point

Single-molecule fluorescence autocorrelation experiments on pentacene: The dependence of intersystem crossing on isotopic composition

The peculiar optic, dielectric and X‐ray diffraction properties of a fluorinated de Vries asymmetric diffuse cone‐model ferroelectric liquid crystal

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