Ali Khumaeni
Departemen Fisika Fakultas Sains dan Matematika, Universitas Diponegoro
Articles
4
Documents
Penghitungan Rasio Intensitas Ca (II) 396,8 nm dan Ca (I) 422,6 nm pada Sampel Tasbih Asli dan Imitasi menggunakan Metode Laser Induced Shock wave plasma (LISPS)

BERKALA FISIKA Vol 9, No 2 (2006): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

Spectral analysis of elemental bead samples has been done using Laser Induced Schock Wave Plasma (LISPS). This experiment is aim to distinguish between bead samples from fresh white coral and its artificial from hardwood through determination of spectral intensity of Ca(II) 396,8 nm and Ca(I) 422,6 nm. The samples are held by 10 torr and induced by NdYAG Laser 1064 nm in wavelength. Results show that the original and artificial samples can be distinguished from ratio of intensity at 1,68 : 0,80 both for white coral and its artificial from hardwood through determination of spectral intensity of Ca (II) 396,8 nm dan Ca (I) 422,6 nm respectively.

STUDY OF ELECTROOPTICS BEHAVIOUR OF NAPHTHALENE AND ANTHRACENE

BERKALA FISIKA 2015: Berkala Fisika Vol. 18 No. 3 Tahun 2015
Publisher : BERKALA FISIKA

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Abstract

In this paper, we demonstrate electro-optics behaviour of naphthalene and anthracene using change of polarization of sample induced by external electric field. The source of light for polarization was 1 mW-he-ne Laser 633 nm. The induced external Electric field was produced by high DC voltage 0 – 7 kV. The samples were diluted in solutions-form using wash-benzene. The result shows that anthracene has higher polarizability than naphthalene, which is indicated by higher change of polarization in anthracene than naphthalene. The Assumption that potential difference is proportional to the distance between molecules is shown qualitatively by graphs of Van der Waals potential energy or force between molecules. In this case, anthracene has higher level Energy than naphthalene so that it can be used in visible excitation for environmental spectroscopy. Keywords: electro-optics, polarization, naphthalene, anthracene, Van der Waals potential energy 

Studi Metode Spektroskopi Plasma Laser Tekanan Rendah untuk Identifikasi Unsur Tembaga

YOUNGSTER PHYSICS JOURNAL Vol 5, No 4 (2016): Youngster Physics Journal Oktober 2016
Publisher : Jurusan Fisika, Fakultas Sains dan Matematika, Universitas Diponegoro

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Abstract

The study on laser plasma spectroscopy has been conducted in Optoelectronics and Laser Laboratory, Physics Department, Diponegoro University, to identify the copper spectrums in samples of pure copper and copper alloys. In this study, some of the tested parameters are the comparison of ambient pressure, laser energy and types of sample. In comparative study on ambient pressure, the researcher compared the plasma laser and the spectrum that is constructed of pure copper at the pressure of 1 atm and 3 Torr with PFN 85%. The study on varieties of laser energy was conducted with the PFN values used on pure copper sampel which is at 3 Torr condition, between the range of 75%, 80%, 85%, 90% and 95%. In the test on sample types, the samples used are pure copper, commercial copper, brass key (Cu-Zn) and bronze coin (Cu-Al), at the pressur of 3 Torr and PFN 85%.. As the result, the plasma on ambient pressure of 3 Torr were formed bigger than at 1 atm and it has more clear and better colored spectrum. The higher value of laser’s PFN also lead to greater formed plasma. The dominant and consistent spectrums formed are Cu I 521,82 nm, Cu I 515,32 nm, Cu I 510,56 nm and Cu I 406,26 nm. Based on the calculation conducted by using the Boltzmann plot method, the value f plasma’s temperature that has been formed is rangen in value of 9503,37 – 10906,54 Kelvin.

Mesh-Assisted Laser-Induced Plasma Spectroscopy Using Pulse Carbon Dioxide Laser for Analysis of Powder Material by Confining the Powder in a Hole and Employing a Condensation Technique

Indonesian Journal of Chemistry Article in press
Publisher : Universitas Gadjah Mada

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Abstract

Analysis of impurity in powder samples has been made by using metal-assisted laser-induced plasma spectroscopy utilizing a pulsed CO2 laser. Various powders including food powder, supplement powder, baby powder, and medicine powder were employed as sample materials. Experimentally, the powder sample was tightly put in a hole made on a metal plate and a metal mesh was placed on the powder surface. A pulse CO2 laser (10.6 μm, 1500 mJ) was irradiated on the powder surface passing through the metal mesh. Luminous plasma was induced by mesh just above the mesh when a part of laser energy attacked the mesh. The other part of laser energy impinged the powders and ablated fine particles of powder to the plasma to be atomized and excited. Identification and analysis of elements in powder were successfully conducted. A linear calibration curve of Cu in baby powder has been demonstrated with an intercept zero, certifying that the present technique was a high possibility to be employed for semi-quantitative analysis of elements in powder material. It was proved that by applying the present technique and employing a condensation technique, the detection sensitivity of Cr impurity in the powder sample increased about twenty times compared to the case without condensation. The limit of detection of Cr in rice powder sample was 25 mg/kg. The proposed method was very convenient for the identification and analysis of elements in the powder sample.