Coupling between the Protons and PO4 Tetrahedra in H+-ion-irradiated TlH2PO4

한덕영,한준희,이철의,이광세,김세헌 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.9

We studied hydrogen-bonded TlH$_2$PO$_4$ (TDP) ferroelectrics treated with proton-beam bombardment. TDP material was irradiated with a 1-MeV proton beam at a dose of 10¹⁵/cm<su>2</sup>. To analyze the local microscopic structure of TDP, we conducted ¹H combined rotation and multiple pulse spectroscopy (CRAMPS), nuclear magnetic resonance (NMR), and high-resolution ³¹P NMR measurements. The isotropic chemical shifts of hydrogen and phosphor nuclei exhibited displacive features throughout the antiferroelectric, ferroelastic, and paraelastic phase that attributed to the interplay of PO₄ lattice deformation and the microscopic hydrogen bond network. The temperature dependence of the isotropic chemical shift σ_iso in ¹H and high resolution ³¹P NMR revealed that the electronic charge redistribution is induced by proton-beam irradiation and the material's elastic properties. We examined the proton-lattice relationship in terms of the proton's location in a local double minimum well and the displacive character of the PO₄ lattice.

Observation of Hydrogen-Bond Modification in Proton-Irradiated KH2PO4

한덕영,J. H. Han,이철의,김세훈 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6

We have studied the microscopic structure of a proton-irradiated KH2PO4 (KDP) single crystal. In solids, the strong dipolar interaction is an obstacle to observing the weaker chemical shift that porvides information on the molecular structure. Therefore, the dipolar interaction must be removed to observe the chemical shift. Our 1H combined rotation and multiple pulse spectroscopy (CRAMPS) nuclear magnetic resonance (NMR) measurement indicates that proton irradiation causes an increase in the isotropic chemical shift, implying a fine structural modification of the O-H…O hydrogen bonds in the paraelectric phase.

Charge Distribution of O-H· · ·O Bonds in Proton-Irradiated KH2PO4 Ferroelectrics

한덕영,J. H. Han,이철의,S. A. Chae,김세헌 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.1

The mechanism of charge distribution has been probed by measuring the 1H chemical shift on a proton-irradiated KH2PO4 (KDP) single crystal. For high-resolution 1H chemical shift measurements,the CRAMPS (combined rotation and multiple pulse sequence) technique is utilized. The proton irradiation caused an increase in 1H chemical shift that can be interpreted as an electronic charge transfer from the proton to an oxygen atom, accompanied by a displacement of the proton along the hydrogen bond. The calculated Morse potentials can be explained by using evidence of electronic instabilities related to the proton displacive features.

Charge Flow in KH₂PO₄ Lattice Structure by Using the Proton-Beam Irradiation.

한덕영,한준희,이철의,김세훈 한국자기공명학회 2008 Journal of the Korean Magnetic Resonance Society Vol.12 No.2

The mechanism of charge flow has been probed by measuring the 1H chemical shift on a proton-irradiated KH2PO4 (KDP) single crystal. The proton irradiation caused the increase in 1H chemical shift. It can be interpreted as the electronic charge transfer from the proton to oxygen atom, accompanied with the proton displacement along the hydrogen bond. For the high resolution 1H chemical shift measurement, CRAMPS (Combined Rotation And Multiple Pulses) technique is utilized.

한국의 인구문제와 인구조절정책

한덕영 중앙대학교 정경대학 학생회 1970 政經論集 Vol.2 No.1

초고해상도 미세영상 기법을 이용한 Mouse 뇌의 자기공명영상 연구

한덕영,윤문현,최보영 대한자기공명의과학회 2008 Investigative Magnetic Resonance Imaging Vol.12 No.2

Purpose : By using the micro-imaging unit modified from NMR spectrometer, the high resolution MRI protocols of finer than 100 micron in 5 minutes, is sought for mouse, which plays a central role in animal studies Materials and Methods : C57BL/6 mouse, lighter than 50 gram, is used for the experiments. The superconducting magnet is vertical type with 89 mm inner diameter at 4.9 Tesla. The diameter of rf-coil is 30 mm. Mostly used techniques are the fast spin echo and the gradient echo pulse sequence. Results : For 2D images, proton density and T2 weighted images are obtained and their optimum experimental variables were sought. Minute structure of mouse brain can be recognized and 3D brain image is also obtained additionally. 3D image will be useful particularly for the dynamic contrast study using various contrast agents. Conclusion : Like the case of human and other small animals, the high resolution of mouse brain is enough to recognize the minute structure of it. Recently, similar studies are reported domestically, but it seems only a beginning stage. Due to easiness of breeding /control, mouse MRI study will soon play a vital part in brain study.

Observation of Hydrogen Localization Induced by Proton-beam Stress in TlH2 PO4

한덕영,J. H. Han,이철의,이광세,김세훈 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.61

We have studied the microscopic structure of a proton-irradiated TlH2 PO4 (TDP) sample under several temperature. The polycrystalline TDP sample was irradiated by a 1-MeV proton beam at a dose of 10 15/cm2. In general, solid materials exhibit a proton strong dipolar interaction and anisotropic chemical shifts that cause spectral line broadening and thereby hinder the observation of the crystal structure. Therefore, in order to determine the hydrogen displacements in the hydrogen bonds, one must eliminate dipolar interactions and anisotropic chemical shifts by using a high-resolution technique. Our1H combined rotation and multiple-pulse spectroscopy (CRAMPS) nuclear magnetic resonance (NMR) measurements indicate that the proton-irradiation stress causes a local strain change, implying the existence of a proton displacive component remaining on the structural modification of the O-H· · ·O bonds.

SiOC(-H) 박막 제조용 Methyltriphenylsilane 전구체 합성 및 특성분석

한덕영,박재현,이윤주,이정현,김수룡,김영희,Han, Doug-Young,Park Klepeis, Jae-Hyun,Lee, Yoon-Joo,Lee, Jung-Hyun,Kim, Soo-Ryong,Kim, Young-Hee 한국재료학회 2010 한국재료학회지 Vol.20 No.11

In order to meet the requirements of faster speed and higher packing density for devices in the field of semiconductor manufacturing, the development of Cu/Low k device material is explored for use in multi-layer interconnection. SiOC(-H) thin films containing alkylgroup are considered the most promising among all the other low k candidate materials for Cu interconnection, which materials are intended to replace conventional Al wiring. Their promising character is due to their thermal and mechanical properties, which are superior to those of organic materials such as porous $SiO_2$, SiOF, polyimides, and poly (arylene ether). SiOC(-H) thin films containing alkylgroup are generally prepared by PECVD method using trimethoxysilane as precursor. Nano voids in the film originating from the sterichindrance of alkylgroup lower the dielectric constant of the film. In this study, methyltriphenylsilane containing bulky substitute was prepared and characterized by using NMR, single-crystal X-ray, GC-MS, GPC, FT-IR and TGA analyses. Solid-state NMR is utilized to investigate the insoluble samples and the chemical shift of $^{29}Si$. X-ray single crystal results confirm that methyltriphenylsilane is composed of one Si molecule, three phenyl rings and one methyl molecule. When methyltriphenylsilane decomposes, it produces radicals such as phenyl, diphenyl, phenylsilane, diphenylsilane, triphenylsilane, etc. From the analytical data, methyltriphenylsilane was found to be very efficient as a CVD or PECVD precursor.

Solid-State High-Resolution ¹H-NMR Study for Ammonia Borane of Hydrogen Storage Material

한덕영,한준희,이철의,김세훈,김창삼 한국자기공명학회 2010 Journal of the Korean Magnetic Resonance Society Vol.14 No.1

In liquids NMR, 1H is the most widely observed nucleus, which is not the case in solids NMR. The reason is due to the strong homo-dipolar interactions between the hydrogen atoms which mask the useful chemical shift information. Therefore we must remove the strong homo-dipolar interactions in order to get structural information, which can be investigated by the isotropic chemical shift. There are two ways of obtaining it. One is the ultra-fast MAS of ca. 70 kHz spinning speed, which has become available only recently. The other way is devising a pulse sequence which can remove the strong homo-dipolar interaction. In the latter way, MAS with a moderate spinning rate of a few kHz, is enough to remove the chemical shift anisotropy. In this report, 1D-CRAMPS and 2D MAS-FSLG techniques are utilized and their results will be compared. This kind of high-resolution 1H NMR for solids, should become a valuable analytical tool in the understanding and the developing of a new class of hydrogen storage materials. Here ammonium borane -NH3BH3, whose hydrogen content is high, is used as a sample.

Elucidation of central line refocusing in quadrupolar echo formation

한덕영 한국자기공명학회 1999 Journal of the Korean Magnetic Resonance Society Vol.3 No.1

Quadrupolar interaction is a strong line broadening agent for nuclei of half-integer spin except the central line. The two-pulse quadrupolar echo technique is widely used, which refocuses the quadrupolar broadening. Echo formation is due to the cancellation of quadrupolar broadening effect by the applied two pulses. Since the central line is not quadrupolar broadened, it should not be involved in the echo formation. However, the central line peak always appears in experiments. This is explained qualitatively here by close examination on the time development of individual coherence. This explanation is used to predict the number of echoes that will be formed with 2 pulse sequence for nuclei of I = 3/2, 5/2, 7/2, 9/2 with ease 영어논문