Bound state solution of the Schrodinger equation for Mie potential

Exact solution of Schrodinger equation for the Mie potential is obtained for an arbitrary angular momentum. The energy eigenvalues and the corresponding wavefunctions are calculated by the use of the Nikiforov-Uvarov method. Wavefunctions are expressed in terms of Jacobi polynomials. The bound states are calculated numerically for some values of l and $n$ with n<5. They are applied to several diatomic molecules.Comment: 10 page

Exact solution of Effective mass Schrodinger Equation for the Hulthen potential

A general form of the effective mass Schrodinger equation is solved exactly for Hulthen potential. Nikiforov-Uvarov method is used to obtain energy eigenvalues and the corresponding wave functions. A free parameter is used in the transformation of the wave function.Comment: 9 page

Bazı kuvantum mekanik sistemlerde tek boyutlu konuma bağlı efektif kütle problemi çalışması.

The one dimensional position dependent effective mass problem is studied by solving the Schrödinger equation for some well known potentials, such as the deformed Hulthen, the Mie, the Kratzer, the pseudoharmonic, and the Morse potentials. Nikiforov-Uvarov method is used in the calculations to get energy eigenvalues and the corresponding wave functions exactly. By introducing a free parameter in the transformation of the wave function, the position dependent effective mass problem is reduced to the solution of the Schrödinger equation for the constant mass case. At the same time, the deformed Hulthen potential is solved for the position dependent effective mass case by applying the method directly. The Morse potential is also solved for a mass distribution function, such that the solution can be reduced to the constant mass case.Ph.D. - Doctoral Progra

Incommensurate faz içeren ferroelektrik kristallerde bellek etkisinin incelenmesi

TÜBİTAK TBAG Proje197T02402.03.1999Bu proje ile incommensurate (IC) yapı içeren ferroelektrik kristallerden TlIn$S_2$ kullanılarak yapılan bir seri deney sayesinde bu çeşit kristallerde görülen ısıl bellek ılayının daha iyi anlaşılması amaçlanmıştır. Bu amaca yönelik olarak pyroelektrik akım, karanlık akım, fotoiletkenlik ve ısıl uyarılmış akım ölçümleri gerçekleştirilmiş ayrıca pyroelektrik akım yöntemi kullanılarak TlIn$S_2$ kristalinin sıcaklığa bağlı spontan polarizasyonu geniş bir sıcaklık aralığında (80-300K) ölçülmüştür. TlIn$S_2$ kristali ile yapılan deneylerde ısıl bellek olayı literatürde kullanılan diğer kristallere göre (1-6) çok daha bariz olarak gözlenmiştir. TlIn$S_2$ kristallerinde, paraelektrik-ICF geçiş sıcaklığı literatürde 216 K olarak verilmesine rağmen, ICF özelliğinin 199K-238 K arasında sürdüğü tesbit edilmiştir. Ard arda ölçümlerde azalarak belli CF-ICF geçiş sıcaklığına ulaşan numunenin 10 saat süreyle 80 K'de saklanmasıyla faz geçiş sıcaklığında -3 K artış gözlenmiş, ancak daha yüksek sıcaklıklardaki saklamaların faz geçiş sıcaklığını değiştirmediği tesbit edilmiştir.Kısa süreli ısıl işlemle yazılanların yine kısa sürede bellekten silinmesi beklenirken kilitkenen IC fazın relaksasyon süresinin beklenenin tersine kısa olmadığı gözlenmiştir. Yukarıda adı geçen hepsi fakat özellikle Isıl Uyarılmış İletkenlik spektrumunun ard arda yapılan ölçümler surasındaki ısıl işlemden kaynaklanan değişimler dikkatle izlenmiştir. Böylece literatürde en çok kabul gören "Kusur Yoğunluk Dalga" (KYD) modelinde öngörülen hareketli yük tuzaklarının varlığı deneysel olarak gözlenmiş ve tuzak parametrelerindeki değişimler hesaplanmıştır. Etki, yukarıda adı geçen modele bağlı kalınarak kristalin tabakalı yapısından kaynaklanan çok sayıdaki hareketli yük tuzaklarının varlığına atfedilmiştir

Characteristics of traps in TlInS2 single crystals

Characteristics of charge traps in TlInS2 single crystals are investigated by the use of thermally stimulated current (TSC) technique. The TSC spectra of the sample from 80 K to 300 K are recorded at a constant heating rate. The spectra reveal that there are several trapping levels associated with the complex structure of overlapping peaks. The experimental results indicate that the traps in TlInS2 associated with the spectra in the measuring range of temperature obey the monomolecular (first order) kinetics. Thus, the spectra are resolved into first order shaped peaks by the use of computerized best fit procedure. The trapping parameters; such as the energy depth, temperature dependent frequency factor and capture cross section, together with concentrations of the corresponding six discrete levels are computed. These centers all having low capture cross sections with strong temperature dependence are found to be at the energies of 0.11 eV, 0.22 eV, 0.25 eV, 0.26 eV, 0.29 eV and 0.30 eV with high concentrations of 6.6 x 10(16), 2.0 x 10(17), 3.3 x 10(17), 9.6 x 10(16), 2.3 x 10(17) and 4.0 x 10(17) cm(-3), respectively. (C) 2013 Elsevier B. V. All rights reserved

Photoelectrical properties of TlGaSe2 single crystals

The spectral distribution of photocurrent (PC) of TlGaSe2 single crystals in the range of wavelengths between 500 nm and 700 nm possesses a single maximum at 2.04 eV corresponds to the direct energy band gap of this crystal. The PC is enhanced dramatically by pre-illuminations at low temperatures with band gap light. The temperature dependence of PC of the sample investigated in the temperature range from 80 K to 300 K at constant heating rate shows that the overlapping peaks in the PC spectrum are direct reflection of the Thermally Stimulated Current (TSC) associated with the several trapping levels. The PC response is strongly dependent on the degree of occupancy of traps. The wavelength at the maximum of the PC spectrum is found to be dependent on the wavelength scan direction being up or down. The ferroelectric phase transitions of TlGaSe2 are detected at similar to 108 K and similar to 118 K in the PC spectrum. (C) 2014 Elsevier Masson SAS. All rights reserved

Characteristics of traps in AgIn5S8 single crystals

Characteristics of charge traps in AgIn5S8 single crystals are investigated by the use of Thermally Stimulated Current (TSC) technique. The TSC spectra of the unintentionally doped sample recorded at a constant heating rate from 80 K to 300 K reveals a single broad peak at similar to 90 K. The shift of the TSC peak continuously due to post-illumination preheating process confirmed the continuous trap distribution, which is Gaussian in shape. The trap density distribution changes from similar to 40 meV on the shallow side to similar to 120 meV on the deep side with the appearance of a maximum at similar to 72 meV

Photocurrent analysis of AgIn5S8 crystal

The photocurrent (PC) spectrum of AgIn5S8 crystal consists of a single peak, which provides to determine the bandgap energy by applying the Moss rule. The temperature dependence of the bandgap energy was also calculated. The PC dramatically increased by pre-illumination with light having wavelength corresponding to the bandgap of AgIn5S8. The temperature-dependent PC of the sample was measured at different temperatures from 80 to 300 K and the PC spectrum consisted a single broad peak. Thermal quenching of the PC was observed to start at similar to 105 K and the PC completely quenched at similar to 180 K. The quenching mechanism was discussed in terms of the two-centre model. The height of the PC peak rised linearly with applied voltage up to 5.0 V under constant intensity of light. Similarly, the dark current-voltage characteristics consisted of a single region dominating an ohmic behaviour, and no space charge limited region was apparent at various temperatures up to 20 V