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"ABSTRACTAn comprehensiove study has been carried out for the study and extension of lases induce shock wave plasma spectroscopy (LISPS) application to non metalic soft and hard samples. For this purpose, a series of experiments were conducted to investigate the dynamical process taking place in the laser plasma generated by a high power and short pulse laser irradiations on a non metal soft and hard samples it was found that in the case of non metal soft sample, the ablated atoms failed to induce a visible plasma at the surface of the target however, it became possible, after a few laser shots depending on the target layer thickness, to generate the sock wave plasma emitting the characteristic spectral line of the target material.Another related phenomenon studied in this experiment is the pre-irradiation effect pbserved on a non metal hard sample such as quartz sample, which was characterized by absence of secondary plasma at athe initial shots. The disappearance of this effect at a later stage was found to be connected with the appearance of a crater of appropriate depth on the sample surface created by iniatial repeated irradiations on the sample surface. The plasma produced thereafter exhibited typical features of a secondary plasma. Further experiment employing aaratificial ring crater on the sample surface has eliminated the pre-irraduation effect completely, and has thus demonstrated that it is the confinenement effect of the crater which was solely responsible for the generation of secondary plasma from the non metal hard tearget. This conclusion is ini confrormation with the shock wave proposed earlier.These experimental studies have thus considerably substantiated our understanding of the process of secondary plasma generatuion. In turn, this result helps to improve the quality and extend the scope of LISPS applications in the future"

"ABSTRACTAn comprehensiove study has been carried out for the study and extension of lases induce shock wave plasma spectroscopy (LISPS) application to non metalic soft and hard samples. For this purpose, a series of experiments were conducted to investigate the dynamical process taking place in the laser plasma generated by a high power and short pulse laser irradiations on a non metal soft and hard samples it was found that in the case of non metal soft sample, the ablated atoms failed to induce a visible plasma at the surface of the target however, it became possible, after a few laser shots depending on the target layer thickness, to generate the sock wave plasma emitting the characteristic spectral line of the target material.Another related phenomenon studied in this experiment is the pre-irradiation effect pbserved on a non metal hard sample such as quartz sample, which was characterized by absence of secondary plasma at athe initial shots. The disappearance of this effect at a later stage was found to be connected with the appearance of a crater of appropriate depth on the sample surface created by iniatial repeated irradiations on the sample surface. The plasma produced thereafter exhibited typical features of a secondary plasma. Further experiment employing aaratificial ring crater on the sample surface has eliminated the pre-irraduation effect completely, and has thus demonstrated that it is the confinenement effect of the crater which was solely responsible for the generation of secondary plasma from the non metal hard tearget. This conclusion is ini confrormation with the shock wave proposed earlier.These experimental studies have thus considerably substantiated our understanding of the process of secondary plasma generatuion. In turn, this result helps to improve the quality and extend the scope of LISPS applications in the future"

"A TEA CO2 laser pulse (50 mJ, 100 ns) was focused under reduced pressure on the silicone grease painted on copper plate as a sub-target with a power density of 6 GW/cm2. The comparison was made on the characteristics of the induced laser plasma between the two cases, with sub-target and without sub-target. It is proved that emission spectrum assigned to silicone atom can be detected only for the case with sub-target. It is also proved that in the absence of the sub-target, the gushing speed of the atoms is very low, while for the case with sub-target, the gushing speed of atoms becomes very fast. It is shown that the setting of sub-target is very effective to make laser-induced shock-wave plasma and it is very effective to realize quantitative analysis of soft material."

"Analisis spektrokimia pada sampel besar seperti plat logam telah dilakukan dengan menggunakan sebuah ruang oakum kecil yang terhubung secara langsung dengan permukaan sampel melalui cincin berbentuk O. Teknik ini menghasilkan plasma yang dapat digunakan untuk analisis in-situ, sehingga prosedur penyiapan sampel yang relatif kurang praktis dapat diatasi. Di samping itu, dengan adanya cincin O yang menempel pada sampel, secara effektif menghalangi emisi kontinu yang tidak diinginkan dari plasma primer, sehingga meningkatkan sensitifitas deteksi dari teknik ini. Selanjutnya dalam eksperimen ini spektrum yang didapatkan dengan menggunakan sistem OMA tanpa fungsi gating masih menunjukkan sinyal latar belakang yang lebih rendah daripada yang didapatkan dengan metode LIBS (Laser induced Breakdown Spectroscopy)."

"The basic principles for the development of laser, an acronym for: light amplification by stimulated emission of radiation, can be traced back to the paper written by Einstein in 1916 when he considered interaction of radiation and matter. In this paper Einstein predicted the existence of stimulated emission and' calculated the probability of its occurence. However, at thermal equilibrium the probability of absorption is larger than stimulated emission therefore the net effect is that light is always absorbed. The stimulated emission can be observed when some population inversion is generated in the material. In order to induce inverted population, one needs to have a proper understanding of the energy level scheme of the material.As a number of atomic or molecular spectra were successfully elucidated by workers in microwave spcectroscopy, the possibility of microwave amplification using stimulated emission from a system of inverted population became a subject of serious investigation. Experimentally the first operation of this amplifier was demonstrated by Townes et.al using amonia molecular beam. The name laser, acronym for: microwave amplification by stimulated emission of radiation, was proposed by this group.In 1958, Schawlow and Townes considered the feasibility of maser action at optical frequencies. In 1960, Maiman succeeded in operating a pulse ruby laser, while Sorokin et.al,demonstrated the infrared pulsed oscilla-Lion using a CaF2 crystal. The first continuous wave laser announced in 1961 by Javan et. Al. Since then, the development of laser progressed rapidly. At present laser oscillation can be obtained in a number of materials such as gas, solid state, semi-conductor, liquid (organic dye) and others. The oscillation wave length of these lasers covers the range from vacuum ultraviolet to far-infrared radiation. Table 1.1. shows the historical sketch of laser developments.The application of lasers covers a wide area of scientific and technological activities and taking advantages of laser a number of novel techniques have been developed in modern science and engineering. The application of laser may be divided into four categories as shown in Table 1.2 T based on the characteristics of laser radiation. The first is the use of energy density with typical examples in material processing and heating. The second is in the use of spatial characteristics of laser which is highly directional. Interferometric measurement and holography are examples in this category."

"ABSTRAKDengan mengfokuskan berkas pulsa laser karbon dioksida pada berbagai macam target pada tekanan rendah, akan terbentuk plasma yang unik. Dalam disertasi ini struktur dan dinamika dari plasma yang unik ini dapat diperoleh dengan mengembangkan metode pengamatan plasma yang baru yaitu pengukuran distribusi ruang dari intensitas emisi pada berbagai waktu tunda. Plasma ini terdiri atas daft bagian; pertama yaitu bagian kecil dari plasma (disebut plasma primer) yang memancarkan spektrum emisi kontinu hanya untuk beberapa seat diatas permukaan target. Bagian yang lain (plasma sekunder) mengembang sesuai waktu disekeliling plasma primer, memancarkan spektrum garis atomik yang sangat tajam dengan emisi latar belakang yang sangat rendah.Juga ditunjukan bahwa emisi dari atom-atom yang terpancar keluar dari target membentuk struktur kulit (tipis), dan ionisasi dari atom-atom berlangsung lebih lambat dari pada eksitasi dari atom-atom netral. Laju pergeseran dari muka emisi adalah sebanding dengan waktu pangkat due per lima. Juga berhasil diamati bahwa titik dimana sinyal emisi mulal tampak adalah sama untuk berbagai macam target meskipun berbeda pada berat atomnya. Hasil ini mendukung model bahwa plasma sekunder dibentuk mengikuti prinsip gelombang kejut dengan plasma primer sebagai sumber energi awal.Dengan memakal gas helium dan argon disekeliling target pada tekanan rendah, dua proses eksitasi yang berbeda terjadi pada saat pembentukan plasma sekunder. Proses eksitasi pertama disebabkan oleh mekanisma gelombang kejut, sedangkan eksitasi kedua disebabkan oleh tingkat energi metastabil pada gas mulia. Proses eksitasi kedua ini menyalurkan energi metastabil yang disimpan oleh gas mulia pada atom-atom yang dipancarkan oleh target meskipun lama setelah pulsa laser berakhir, sehingga menghasilkan intensitas emisi yang lebih tinggi di gas mulia dibandingkan di udara.Temperatur tinggi pada plasma sekunder sebagai akibat dari kecepatan propagasi yang tinggi dari muka plasma menyebabkan plasma ini sangat cocok digunakan untuk mendeteksi atom-atom halogen yang biasanya sangat sukar diidentifikasi karena tingkat energinya yang sangat tinggi. Aplikasi analitis untuk mendeteksi unsur halogen pada contoh bubuk kimia maupun kalsium pada bahan makanan menunjukkan hubungan yang linter pada kurva kalibrasi. dalam metode Laser Microprobe Spectrochemical Analysis (LHSA) yang umum dipakai hingga saat ini untuk analisa spektrokimia, tidak terdapat hubungan yang tinier pada kurva kalibrasinya karena timbul penyarapan sendiri (self absorption) yang sangat kuat, .lumlah minimum yang dapat dideteksi untuk Cl adalah 5 ppm dan 10 ppm untuk Ca, yang mane Jauh lebih balk dibandingkan dengan metode Induction Couple Plasma (ICP) maupun metode lain. Hingga saat ini metode ICP adalah metode ter-balk yang banyak dipakal untuk analisa elemen-elemen pads bahan makanan. Metode kami akan dikembangkan menjadi metode analisa kuantitatif yang cepat, akurat dan. memiliki sensitivitas yang tinggi tidak Baja pada bahan makanan tetapi juga pada bahan biologi, geologi dan lain-lain.

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ABSTRACT

A study has been conducted on the formation of the unique plasma generated by focusing a TEA CO2 laser onto various targets with low pressure surrounding gases. A new method of time-resolved measurement of spatial distribution of the plasma was carried out for analyzing the plasma structure and dynamics. The unique laser induced plasma consists of two distinct regions; the first is a small area of plasma (called primary plasma), which gives off intense continuous emission spectra for a short time just above the surface of the target. The other area (secondary plasma) expands with time around the primary plasma, emitting sharp atomic line spectra with negligibly low background signals.

It is clearly shown that emission due to the gushed atoms from the target form shell structure, and the ionization of the atoms proceeds at slower rate than the excitation of the neutral atoms. The displacement of the emission expansion is proportional to the two-fifths power of time. It has been also observed that the rising point in the time-resolved spatial distribution of the emission 1s the same regardless of the difference in atomic weight. These results support the model that the secondary plasma is excited by a shock wave with primary plasma serving as the initial explosion source.

By using helium and argon as a surrounding gases, two different excitation processes take place in farming the secondary plasma. The first excitation process is due to the shock wave mechanism, while the second process is due to the metastable state of the noble gases. It is believed that this second process transfers metastable energy to the vaporized atoms of the target for emission, even long after the laser bombardment ends, thus giving total emission intensity that is higher in the noble gases than yielding in air.

The high temperature generated in the secondary plasma as a result of its high propagating front speed has made it favorable for use in detecting atoms such as halogens which are usually very difficult to identify because of their high lying electronic energy level. Analytical application to the detection of halogen atoms in chemical powder and calcium in food material shows good linearity in the calibration curve. In the ordinary Laser Microprobe Spectra-chemical Analysis (LMSA), the calibration curve is not linear due to the strong self absorption. The detection limit of Cl, Ca is 5 ppm and 10 ppm respectively which is-better than ICP (50 ppm for Cl) and other methods. So far, ICP emission spectrometry has been used as the most convenient method for simultaneous multi elemental analysis of food materials. Our method will be developed as a rapid, high-precision, highly sensitive quantitative analytical method for not only food materials but also other biological and geological samples."

"ABSTRAKSaat ini teknologi nuklir berkembang dengan baik di Indonesia dan pemanfaatannya baik di bidang kesehatan, pertanian, peternakan, industri dan energi digunakan sepenuhnya untuk kesejahteraan seluruh masyarakat Indonesia. Dalam pengembangan dan pemanfaatan teknologi nuklir tentu harus mempertimbangkan dan meminimalisir efek bahaya dari radiasi nuklir, baik untuk pekerja yang berada dilingkungan instalasi nuklir maupun bahaya kontaminasi lingkungan disekitar instalasi nuklir. Untuk itu kegiatan pemantauan, pendeteksian dan pengukuran radiasi mutlak diperlukan. Umumnya kegiatan pemantauan, pendeteksian dan pengukuran radiasi dilakukan dengan perangkat deteksi nuklir. Pada penelitian kali ini dilakukan metode alternatif pengukuran, analisis dan identifikasi unsur radioaktif dengan teknik laser induced plasma spectroscopy LIPS . Penggunaan teknologi LIPS dipilih karena LIPS adalah suatu teknik analisis sampel secara in situ, kualitatif dan kuantitatif yang cepat, dan hampir tanpa preparasi sampel. Analisis dan identifikasi unsur radiaoaktif dilakukan dengan menembakkan laser pulsa NdYAG Q-Switch 355 nm, 10 Hz, durasi pulsa 5.5 ns, f = 100 mm, dengan variasi energi 5.5 mJ - 140 mJ dan dengan variasi tekanan udara 4 Torr ndash; 1 atm pada sampel material radioaktif alamiah atau Naturally Occurring Radioactive Material NORM dengan metoda ablasi laser yang dilanjutkan dengan metoda spectral plasma analisis. Berdasarkan penelitian yang telah dilakukan, secara kualitatif teknik LIPS mampu mengidentifikasi adanya unsur radioaktif Uranium U dan Thorium Th yang terdapat pada sampel uji dengan energi laser optimum sebesar 107 mJ dan secara kuantitatif didapatkan nilai prediksi konsentrasi unsur Uranium sebesar 155 ppm dengan persentase error 11.3 dan nilai batas deteksi sebesar 7.89 ppm, nilai prediksi konsentrasi unsur Thorium sebesar 124 ppm dengan persentase error 8 dan nilai batas deteksi sebesar 12.4 ppm. Dengan kata lain teknik LIPS secara inheren sangat cocok dan sangat memungkinkan digunakan sebagai teknik pengukuran, analisis dan identifikasi keberadaan unsur radioaktif.

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ABSTRACTNuclear technology is currently well developed in Indonesia and its use in the field of health, agriculture, industry and energy is completely used for the welfare of all the people of Indonesia. In the development and utilization of nuclear technology should certainly consider and minimize the effects of nuclear radiation hazards, both for the workers who are in the environment of nuclear installations and the danger of contamination of the environment around nuclear installations. Therefore monitoring activity, detection and measurement of radiation is absolutely necessary. Generally the monitoring activity, detection and measurement of radiation carried by the nuclear detection devices. In this study, alternative methods of measurement, analysis and identification of radioactive elements is carried out by using laser induced plasma spectroscopy LIPS . The use of LIPS technology is selected since LIPS is a technique in situ sample analysis, qualitative and quantitative fast, and almost no sample preparation. Analysis and identification of the radioactive element is carried out by firing laser pulses NdYAG Q Switch 355 nm, 10 Hz, pulse duration of 5.5 ns, f 100 mm, with a variation of the energy 5.5 mJ 140 mJ and with variations in air pressure 4 Torr 1 atm in a sample of Naturally Occurring Radioactive Material NORM with laser ablation method, followed by plasma spectral analysis method. Based on the research that has been done, LIPS technique is qualitatively able to identify the presence of radioactive elements, i.e. Uranium U and thorium Th contained in the test sample with a laser energy optimum of 107 mJ and quantitatively obtained predictive value of elemental concentrations of Uranium of 155 ppm along with 11.3 of percentage error and 7.89 ppm of detection limit value, also the predictive value of the elemental concentration of thorum of 124 ppm along with 8 of percentage error and 12.4 ppm of detection limit value. In other words, LIPS technique is inherently very suitable and it is possible to use as a measurement technique, analysis and identification of the presence of radioactive materials."

"Telah dilakukan upaya untuk mempersempit lebar garis keluaran laser zat warna pulsa dengan menggunakan teknik susunan prisma. Untuk mengamati secara langsung lebar garis spektral keluaran laser, berkas laser didispersikan oleh kisi pantul di dalam suatu alat pengukur panjang gelombang. Uraian panjang gelombang (spektrum warna) yang tampak dari mikroskop pengukur panjang gelombang dipotret dan disajikan dalam bentuk foto-foto. Dengan susunan 4 (empat) prisma diperoleh penyempitan lebar garis dengan faktor -1/17, yakni dari – 0,952 nm menjadi – 0,056 nm. Pengujian lebib lanjut dilakukan dengan menggunakan berkas laser tersebut dalam spektroskopi laser-berkas atom untuk mengamati garis-garis DI dan D2 pada atom Na. Dari pengujian spektroskopi diperoleh lebar garis spektral laser dengan susunan 4 prisma – 0,075 nm"

"This book is a comprehensive source of the fundamentals, process parameters, instrumental components and applications of laser-induced breakdown spectroscopy (LIBS). The effect of multiple pulses on material ablation, plasma dynamics and plasma emission is presented. A heuristic plasma modeling allows to simulate complex experimental plasma spectra. These methods and findings form the basis for a variety of applications to perform quantitative multi-element analysis with LIBS. These application potentials of LIBS have really boosted in the last years ranging from bulk analysis of metallic alloys and non-conducting materials, via spatially resolved analysis and depth profiling covering measuring objects in all physical states: gaseous, liquid and solid. Dedicated chapters present LIBS investigations for these tasks with special emphasis on the methodical and instrumental concepts as well as the optimization strategies for a quantitative analysis. Requirements, concepts, design and characteristic features of LIBS instruments are described covering laboratory systems, inspections systems for in-line process control, mobile systems and remote systems. State-of-the-art industrial applications of LIBS systems are presented demonstrating the benefits of inline process control for improved process guiding and quality assurance purposes."