Q-switched Nd-YAG Laser Research Articles

Melasma Revisited: National Survey Reveals How Dermatologists Diagnose and Treat This Complex Skin Condition.

Melasma is a chronic condition characterized by dark patches on the facial skin. It has a known female gender dominancy, and women usually think of melasma as being a serious cosmetic problem. Treatment of melasma can be seriously challenging, thus, dermatologists may employ different approaches for melasma. This study aimed to investigate how dermatologists diagnose and treat patients with melasma and to present the general characteristics of patients with melasma. A survey was conducted using Google Forms targeting dermatologists in Turkiye. A total of 199 dermatologists (142 females/57 males) participated in the study. Most of the participants (52.3%) were residents. Majority gender of the patients was female and most common age range of patients with melasma was 30-40 years. Mixed melasma was the most common type (57.4%). Malar region was the most frequent location (58.6%). Wood's lamp examination was used by 25.6% of the participants. Topical treatment was the first-line choice for melasma therapy (95%), with Kligman's formula being the most used topical agent (69.8%). Oral therapy was not used by 70.8% of the participants. Tranexamic acid was the first choice for oral treatment (23.4%). Only 24.9% of the dermatologists used laser/light therapy, and Q-switched Nd-YAG laser was the most preferred device (58%). The most common recurrence rate was 41%-60% (45.9%). The findings of the current study investigating the melasma management in Turkiye revealed a female predominance and peak prevalence in the 30-40 years age group. Kligman's formula is the preferred topical treatment, whereas oral tranexamic acid remains underutilized. Recurrence rates are high, highlighting the need for preventative strategies. This study emphasizes the importance of personalized approaches and ongoing research for effective melasma management.

Prospective study of using 1064-nm Q-switched Nd: YAG combined with radiofrequency-imported vitamin C on pigmented infraorbital dark circles

Infraorbital dark circles are a common manifestation of periorbital melanosis, which is aesthetically defective and bring a negative impact on life quality. However, there is no acknowledged treatment for infraorbital dark circles. The 1064-nm Q-switched Nd: YAG laser (QSNYL) is commonly utilized to treat hyperpigmentation disorders. Radiofrequency (RF) therapy can improve the transdermal absorption rate of drugs. A prospective clinical trial was conducted to investigate the clinical efficacy and safety of 1064-nm QSNYL combined with RF-imported vitamin C for the treatment of infraorbital dark circles. A questionnaire was used to explore the relevant factors affecting the severity of infraorbital dark circles. A total of 30 patients with pigmented infraorbital dark circles were enrolled in this clinical trial. Each participant received 4 treatments and was followed up for at least 12 months after the last treatment.We focused on the overall change in the appearance of the included participants before and after treatment, by using satisfaction evaluation.In order to reduce evaluation bias, the vivo reflectance confocal microscopy images were taken on days 1 and 120 to detect pigmentation. The questionnaire survey before treatment showed that high-frequency makeup was positively and statistically significant with the severity of infraorbital dark circles (p < 0.01). Both participants and independent evaluators found that the hyperpigmentation in the infraorbital region was significantly reduced after combined treatment with high treatment satisfaction. The density of melanin particles in the infraorbital dark circles region showed a decreased trend. No significant side effects were observed. The 1064-nm QSNYL combined with RF-imported vitamin C is a safe and effective treatment for pigmented infraorbital dark circles by reducing melanin particles.

Determination of third order nonlinearity (n2 & β) of glycine zinc sulphate pentahydrate semi-organic single crystal using two laser radiations at different intensities

AbstarctThe third order nonlinear optical properties i.e. nonlinear refraction (n2), absorption coefficient (β) and third order susceptibility χ(3) of glycine zinc sulphate pentahydrate (GZS) semi-organic single crystal was investigated under the excitation of Q-switched Nd-YAG laser pulsed radiations (λ = 532 nm & 1064 nm) by familiar Z-scan method. The values of nonlinear refraction (n2), at 532 nm were 1.19 × 10−5 (cm2/GW), 2.09 × 10−5 (cm2/GW), 2.27 × 10−5 (cm2/GW), 2.48 × 10−5 (cm2/GW), and 2.55 × 10−5 (cm2/GW) at incident optical beam intensities of 0.76 (GW/cm2), 1.13 (GW/cm2), 1.17 (GW/cm2), 1.63 (GW/cm2) and 1.88 (GW/cm2) respectively while that of values at 1064 nm were 4.31 × 10−5 (cm2/GW), 4.69 × 10−5 (cm2/GW), 5.41 × 10−5 (cm2/GW) and 6.39 × 10−5 (cm2/GW) at incident optical beam intensities of 1.20 (GW/cm2), 1.25 (GW/cm2), 1.32 (GW/cm2) and 1.38 (GW/cm2) respectively. The values of nonlinear absorption coefficient (β) at 532 nm were −1.45 (cm/GW), −0.79 (cm/GW), −0.5 (cm/GW), 0.12 (cm/GW) and 0.64 (cm/GW) at incident optical beam intensities of 0.76 (GW/cm2), 1.13 (GW/cm2), 1.17 (GW/cm2), 1.63 (GW/cm2) and 1.88 (GW/cm2) respectively while that of values at 1064 nm were 0.62 (cm/GW), 0.74 (cm/GW), 0.77 (cm/GW) and 0.81 (cm/GW) at incident optical beam intensities of 1.20 (GW/cm2), 1.25 (GW/cm2), 1.32 (GW/cm2) and 1.38 (GW/cm2) respectively. The values of third order susceptibilities χ(3) at 532 nm were 0.83 × 10−12 (esu), 1.32 × 10−12 (esu), 1.42 × 10−12 (esu), 1.55 × 10−12 (esu) and 1.56 × 10−12 (esu) at intensities of 0.76 (GW/cm2), 1.13 (GW/cm2), 1.17 (GW/cm2), 1.63 (GW/cm2) and 1.88 (GW/cm2) respectively while that of values at 1064 nm were 2.71 × 10−12 (esu), 2.96 × 10−12 (esu), 3.4 × 10−12 (esu) and 4.02 × 10−12 (esu) at incident optical beam intensities of 1.20 (GW/cm2), 1.25 (GW/cm2), 1.32 (GW/cm2) and 1.38 (GW/cm2) respectively. It was seen that the sample showing saturable absorber to reverse saturable absorber at 532 nm wavelength at incident optical beam peak intensity (I0) of 1.53 GW/cm2. Thus the crystal could be a potential candidate of optical switching application. It was also seen that the material possess positive nonlinearity. It was also found that the values of nonlinear absorption coefficient (β) and nonlinear refraction (n2) increase with increase of excitation intensity irrespective of excitation wavelengths.

Removal of black tattoos by Picosecond Q-switched Nd-YAG laser in the middle eastern skin type IV: prospective study

Tattoo removal is considered a challenging field in cosmetic dermatology. Picosecond Q-switched Nd-YAG lasers targeting unique chromophores effectively manage this condition without serious complications. To evaluate the efficacy and safety of Picosecond Q-switched Nd-YAG laser in the treatment of black tattoos in the skin of middle eastern mostly skin type IV. The study was carried out on 20 patients with skin type IV the most common in middle eastern area with professional black tattoos. They were treated by Picosecond Nd-YAG laser (2 sessions 8 weeks apart). The percentage of improvement ranged from 20.0 to 95.0 (with a mean of 61 ± 24.6). 8 patients (40%) showed excellent improvement, 4 patients (20%) showed marked improvement, 4 patients (20%) showed moderate improvement, and 4 patients (20%) showed mild improvement. No severe side effects were detected. Picosecond Nd-YAG laser was an effective and safe technique in the treatment of professional black tattoos; with only 2 sessions most patients reached excellent to moderate response with minimal side effects.

The treatment of infantile giant café au lait spot using golden parameter therapy with a high fluence 1064-nm Q-switched Nd: YAG laser

Background Infantile café au lait spot is a brown macule with various sizes (diameter: 0.5 cm–30 cm). Infantile giant café au lait spot (IGCALS) is a huge (diameter >20cm) irregular-shaped benign hyperpigmented skin disorder that arises in infants. There has been no clearly established laser treatment consensus for the treatment of IGCALS because infants are too fragile to receive laser treatment with long hours and broad areas along with the possibility of undesirable cosmetic results. Objectives This study investigated the safety and efficacy of Golden Parameter Therapy (GPT) using a high fluence 1064-nm Q-switched Nd:YAG laser (QSNL) for IGCALS treatment. Methods This study included 24 Korean patients with IGCALS. Twenty-one patients who were treated with a 1064-nm QSNL weekly for 30–50 treatment sessions with GPT. The parameters included a spot size of 7 mm, a fluence of 2.2 J/cm2 and a pulse rate of 10 Hz with one pass using a sliding-stacking technique over the IGCALS. In control group, three patients were treated with a 532-nm picosecond laser monthly for three treatment sessions with a spot size of 3 mm, a fluence of 1 J/cm2 and a pulse rate of 2 Hz. Results After the last treatment, 21 patients with IGCALS reached the complete removal of pigmented lesions, which can be considered optimal cosmetic results without any side effects such as purpura, crust, post-inflammatory hyperpigmentation, iatrogenic punctate leukoderma, and scarring. There are no recurrences in any patients after 6–21 months’ follow-up, but treatment failure occurred in three patients who were treated with 532 nm picosecond laser. Conclusions Convincingly, we argue that early intervention before 12 months of age with GPT using a high fluence 1064 nm QSNL is a safe, applicable and effective treatment for IGCALS, minimizing side effects without any recurrences.

Fabricating and examining nanocomposite of P3HT- Graphene- MoS2 by laser ablation method

Abstract This study presents the first successful synthesis of a nanocomposite comprising Poly (3-hexylthiophene) (P3HT), graphene (G), and molybdenum disulfide (MoS2) via laser ablation, using a Q-switch Nd-YAG laser with a repetition rate of 1 (Hz) and different laser pulses of 200, 500, and 800 for both graphene and MoS2, the morphological and optical properties of the samples was thoroughly investigated by various analytical techniques including Transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR), and spectrophotometer UV-Vis. Transmission electron microscopy showed that the graphene and molybdenum nanoparticles were semispherical or ball-shaped, with diameters ranging from 6.7 to 61.7 nm. The UV-Vis findings show that the absorbance and absorption coefficient increase with the number of pulses due to the increased concentration of nanoparticles. The FTIR results confirm strong bonding between the P3HT-G800P/MoS2 800P nanocomposite bonds. The indirect energy gap of the Nanocomposite is estimated to be 1.99 (eV), making it attractive for optoelectronic applications.

A prospective comparative study of efficacy and safety of 15% trichloroacetic acid peel, 35% glycolic acid peel and Q-switched Nd-YAG laser in patients of macular amyloidosis.

The unappealing appearance of skin in macular amyloidosis (MA) interferes with the patient's quality of life, and treating the condition has been challenging. To compare the efficacy and safety of 15% trichloroacetic acid (TCA) peel, 35% glycolic acid (GA) peel, and Q-switched Nd-YAG Laser in MA. Open, prospective study was conducted over 2 years, where after fulfilling the criteria, randomization was done into three groups. Group A: 15% TCA peel; Group B: 35% GA peel; Group C: Q-switched Nd-YAG Laser. Procedures were repeated at monthly intervals for six sittings. On each visit, patients were scored on the following parameters: color score, visual analog score (VAS), physician global assessment (PGA) scale, subjective improvement, and adverse effects. A total of 75 patients (25 patients in each group) completed the treatment. The mean age of study-population was 35.68 ± 9.8 years, with female to male ratio of 11.5:1. The mean change in color score (1.68) was more by Group A, followed by Group C (1.4), followed by Group B (1.16). Similar results were noted by subjective improvement, VAS, and PGA. Adverse events were more in Group A, followed by Group C, followed by Group B. No patient showed permanent adverse events. TCA-peel showed superior results over Nd-YAG laser and glycolic-acid peel. TCA-peel being cost-effective with excellent acceptability should be considered a treatment modality.

Comparing Oral Tranexamic Acid and Q-Switched Nd-YAG Laser for Melasma: A Randomized Study

Comparing Oral Tranexamic Acid and Q-Switched Nd-YAG Laser for Melasma: A Randomized Study

Effect of laser irradiance on opto-electrical properties of PVA embedded graphene copper ferrite nanocomposite strips

The polyviny alcohol (PVA) nanocomposite strips embedded with graphene nanosheets and copper-ferrite nanoparticles were synthesized using solution casting technique. Each synthesized strip was exposed to Q-switched Nd-YAG laser irradiations using three different laser pulse energies of 19 mJ/cm2, 25.5 mJ/cm2 and 31.8 mJ/cm2 for 12 min. The synthesized irradiated and non-irrediated strips were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, UV–visble spectroscopy and frequency response analyzer to investigate the effects of nanofillers incorporation and laser pulse irradiations on structural, optical and electrical modifications. A small incorporation of each nanofiller (0.25 wt %) into the PVA matrix and subsequent laser irradiations have interestingly tuned the structural, optical, and electrical properties including direct bandgap, indirect bandgap, absorption edge, Urbach energy, extinction coefficient, refractive indices, optical conductivity, real and imaginary part of optical dielctric constant, dielectric loss and dielectric constant. The synthesized nanocomposite strips might find their potential in optoelectronic devices.

Wound treatment Q-switched Nd: YAG Laser tattoo removal rat model by Photobiomodulation Therapy PBMT

The Q-switched laser method is the most effective method of tattoo removal compared to other methods of i.e. chemical, mechanical and surgical. The objective of this study is to investigate the effect of Nd:YAG laser to remove the tattoo and also to utilize 808 nm diode laser to enhance the wound healing at post-treatment. Q-switched Nd: YAG laser with fundamental wavelength of 1064 nm is applied to remove tattoo pigment with different energy fluencies. Additionally, 808 nm diode laser will be applied on wound created after tattoo removal to enhance the healing process. More than 15 Sprague Dawley rats will be involved and tattooed with black inks on their back by a tattoo gun. A single session treatment is use in the energy about 400mj for tattoo removal. The exposure to diode laser treatment will be conducted daily. The experimental observation will be hold for 9 days, and 5 rats from each group will be sacrificed on day 3, 6 and 9 respectively. The skin biopsy will be removed for H&amp;E and Masson’s trichrome histology examination. The effect of tattoo removal and healing progress of skin analyzed via photothermal.. The preliminary findings of this study indicate that 1064 nm wavelengths of Q-switched Nd-YAG laser treatment with 400mj pulse energy exhibit significant progress of black tattoo removal.

Crystal design of novel Piperazinum Isophthalate (PIP): Growth, Structural, Thermal, Spectral, Mechanical and Optical properties for NLO application

Novel organic single crystal Piperazinum Isophthalate (PIP) has been synthesized and grown by the slow evaporation solution growth technique. The structural analysis of the single crystal was assessed by the single crystal X-ray diffraction and from a thorough literature survey, it is confirmed that the structure is claims to be the reported for the first time. The FT-IR analysis is used to confirm the different vibrational modes present in the crystal. Utilizing Vicker's Microhardness tester, the mechanical behavior of the crystal was examined and its related constants were computed. Mechanical analysis reveals that the grown crystal exhibits Reverse Indentation Size Effect (RISE) and also found that it belongs to the soft material category with n = 8. The TG/DTA technique is used to analyze the thermal property of the grown crystal and found that PIP is thermally stable up to 271°C. The optical property of the PIP crystal is analyzed using the UV–Vis NIR Spectroscopy, it is observed that PIP has good transparency in the entire visible region with a cutoff wavelength of 281 nm. The Laser Damage Threshold (LDT) of the PIP single crystal was studied by the Q-switched Nd-YAG laser of the wavelength 532 nm and the computed LDT value is 7.3047 GW/cm2. The third order non-linear optical properties of the grown crystal were analyzed by Z - scan technique and the obtained results confirm high nonlinear susceptibility(X(3) = 1.2728× 10−7esu) with self-defousing nature. From the above discussion, we may infer that the grown PIP crystal will be a promising material for optoelectronic device fabrication.

Nonlinear Refraction, Excited State Absorption, and Multiphoton Absorption of 1,3-Thiazolium-5-thiolate Mesoionic Compound.

We synthesized the mesoionic compound 2-(4-chlorophenyl)-3-methyl-4-(4-methylphenyl)-1,3-thiazole-5-thiolate and measured its refractive and absorptive nonlinear optical response in different temporal and spectral regimes. The experiments were performed by using the Z-scan technique with two pulsed light sources: the second harmonic (at 532 nm) of a mode-locked and Q-switched Nd-YAG laser (100 ps, 10 Hz) and a Ti: Sapphire laser system (100 fs, 1 kHz) operating at 800 nm. The observation and characterization of nonlinear refraction, two- and three-photon absorption, and excited state absorption of the mesoionic compound dissolved in dimethyl sulfoxide, in different concentrations, are presented and discussed with basis on the population redistribution in a three-energy-level model that allows the determination of the parameters which characterize the nonlinear response.

Treatment of Benign Melanocytic Hyperplasia of Nail Apparatus with Dr. Hoon Hur’s Golden Parameter Therapy

Background: Benign melanocytic hyperplasia (BMH) of nail apparatus may be caused by a lentigine in the nail matrix. Traditional treatment modalities including surgical excision and CO2 laser ablation may cause a severe scar of nail apparatus.There is no clear treatment for BMH of nail apparatus. Objectives: This study was performed to investigate the efficacy and safety of Dr. Hoon Hur’s Golden Paramter Therapy (GPT) with a high fluence 1064nm Q-switched Nd:YAG laser (QSNL) for treating BMH of nail apparatus . Study design: The medical records of 52 Korean patients (age range: 21 to 60 year-old, mean age: 38.6 year-old) diagnosed with BMH of nail apparatus were reviewed retrospectively. Methods: All patients were treated with a 1064nm QSNL, on a weekly basis for 10-15 treatment sessions of Dr. HoonHur’s GPT. The parameters were a spot size of 7mm, a fluence of 2.2J/cm² and a pulse rate of 10Hz with three passes by a sliding technique (sliding GPT) and one pass by a pulse stacking technique (pulse-stacking GPT) over the BMH of nail apparatus. Results: At the time of the final treatment, all patients with BMH showed the complete removal of pigmented lesions without any side effects, such as purpura, crust, post-inflammatory hyperpigmentation (PIH), nail dystrophy and scarring. No recurrences were observed in any of the patients after a follow-up of 3-12 months. Conclusion: We suggest that Dr. Hoon Hur’s GPT with a high fluence 1064nm QSNL is a safe and effective new treatment for BMH of nail apparatus without side effects and recurrences. Keywords: Benign Melanocytic Hyperplasia; Nail;1064-nm ND:YAG laser;Dr. Hoon Hur’s GPT

A retrospective study of 1064-nm Q-switched Nd:YAG laser therapy for acquired bilateral nevus of Ota-like macules.

The therapeutic efficacy of laser treatments for acquired bilateral nevus of Ota-like macules (ABNOM) varies among studies, and few studies have evaluated the factors affecting therapeutic effects. To evaluate the efficacy and safety of 1064-nm Q-switched Nd:YAG laser (QSNYL) therapy for ABNOM and to identify the factors influencing the outcome. A total of 110 patients with ABNOM were retrospectively evaluated and received two-to-nine treatment sessions. The effects of different factors on the therapeutic effect were analyzed on the basis of the number of treatments, age at first treatment, skin type, lesion color, affected area, number of lesion sites, and presence of concomitant melasma. The curative effect was positively correlated with the treatment time and negatively correlated with the increasing age at first treatment (p<0.05). The curative effect was better in patients with skin type III than those with type IV ( p<0.05) and in patients with a lesion area of less than 10cm2 than those with a larger affected area (p<0.05). Additionally, the treatment effect was poorer in patients with concomitant melasma (p<0.05). The treatment effect was not significantly correlated with the lesion color or number of affected sites (p>0.05). Eleven patients (10%) developed postinflammatory hyperpigmentation (PIH). Early and repeated QSNYL therapy achieved satisfactory results for ABNOM. The risk of PIH after laser treatment is highest among patients with older age, darker lesion color, and darker skin color. For patients with ABNOM with concurrent melasma, low-energy laser therapy is recommended to reduce the risk of melasma aggravation.

Efficacy and safety of Q-switched lasers for the treatment of naevus of Ota in children: a retrospective analysis.

To identify factors influencing the efficacy of Q-switched laser in the treatment of naevus of Ota in children and to compare the efficacy, safety, and recurrence rate between 1064nm Q-switched Nd:YAG laser (QSNL) and 755nm Q-switched alexandrite laser (QSAL). We retrospectively analysed 160 children with naevus of Ota who completed QSAL or QSNL laser treatment at our centre. Age at initial treatment (P = 0.004), colour of lesions (P = 0.025), and number of treatments (P = 0.002) were related to efficacy. Compared with patients aged 0-11months at initial treatment, patients who started treatment at 1-3years (OR adj = 0.47), 4-8years (OR adj = 0.20), and 9-12years (OR adj = 0.27) had inferior efficacy. The efficacy of brown-violet (OR adj = 2.67) and blue-violet lesions (OR adj = 2.51) was better than that of brown lesions. Moreover, patients who received 3-4 (OR adj = 2.83) or 5-6 (OR adj = 7.35) treatment sessions showed a better response than those who received 1-2 sessions. Additionally, as the age at initial treatment increased, the rate of complications increased from 2.0 to 14.3%, while the recurrence rate decreased from 8.2 to 0%. In addition, the complication rate increased with an increase in the number of treatments. There were no significant differences in clinical efficacy (P = 0.94), risk of complications (P = 0.752), or recurrence (P = 0.834) between QSAL and QSNL for treating naevus of Ota in children. QSAL and QSNL are equally effective for children's naevus of Ota, with low complications and recurrence rates. Younger age at initial treatment and a greater number of treatments are beneficial for efficacy, whereas brown lesions are a negative factor.

Optical Properties of Lithium Niobate Nanoparticles Prepared by Laser Ablation in Different Surfactant Solutions

In this paper, the optical, structural, and surface morphology of novel lithium-niobate (LN) colloidal synthesis by ablation in liquid using a pulse laser method has been studied and analyzed for the first time. LiNbO3 suspensions are synthesized using a Q-switch Nd-YAG laser with two target types, each with three different types of liquid environments: deionized water, ethanol, and acetone. The prepared colloidal is to go under further processes to be later used in the photonic application. The optical properties of the suspensions were evaluated by ultraviolet-visible (UV-Visible) measurements. The results showed that the colloidal had a transmission spectrum ranging between 88 to 98% for LN Target and 96 % to 98% for LN Z-cut wafer. The estimated energy gaps are (3.3-3.7 eV) for the prepared target and (4.1-4.3) for the LN Z-cut wafer, which gives good accordance with reported results in the range of ~ 3.7- 4 eV for all samples. In general, the Z-cut wafer target gives better results with ethanol based on optical properties. XRD measurements show the formation of a multi-phase with impurities for a prepared lithium niobate target and multi-phase LiNbO3 films with no impurities or a second phase for another Z-cut wafer. FESEM scan is measured for LiNbO3 films, and the particle size is about 20 and 23 nm.

Optical and Photolumenance Studies of Deposited CuO&lt;sub&gt;2&lt;/sub&gt; Nano-Structures at Different Laser Energies Effects

The deposition of copper oxide utilizing a pulsed laser deposition technique employing a reactive pulsed laser as a deposition technique is the subject of this study (RPLD), 1064 nm, 10 Nanosecond Q-switch Nd-YAG laser with 350 °C, and 800-1200 mJ energies of laser was used to deposited a high purity target of Cupper and deposited on the quartz substrates synthesized and study the laser energies effect on the optical and photoluminescence properties.

Effect of Au and Ag nanoparticles addition on the morphological, structural and optical properties of ZnO thin films deposited by sol-gel method

In the present study, ZnO thin films were deposited on quartz substrates by sol-gel spincoating method. Zinc-diacetate ((Zn(CH3COO)2.2H2O), diolamine (DEA) (HN(CH2CH2OH)2) and ethylene glycol monomethyl ether (CH3OCH2CH2OH) were used as a precursor, stabilizer agent, and solvent, respectively. Au and Ag NPs were synthesized by (PLAL) technique using “Q-Switched ND-YAG laser” system with laser parameters (520 mJ laser energy, 1064 nm wavelength, 450 laser pulses, and 1Hz frequency). The volumetric ratios of ZnO source solution to Au and Ag colloidal solutions were 3:2 and 4:1, respectively. The morphological, structural and optical properties of ZnO thin films embedded with Au and Ag NPs were investigated. The patterns of x-ray diffraction (XRD) showed peaks indexed to (100), (002) and (101) planes for ZnO and (111), (200) and (220) for Au and Ag NPs. The surface morphology of the films was examined by FESEM and the Raman spectra of ZnO thin films embedded with Ag and Au NPs were investigated. Furthermore, the optical properties of the films were analyzed by UV-Vis spectroscopy measurements. The optical band gap of the films increased with increasing the volumetric ratios of ZnO embedded with Au and Ag NPs.

Deposition of MgO Nanoparticles by Laser Pyrolysis

Magnesium oxide nanoparticles were deposited by laser pyrolysis process. Three types of lasers were employed CW CO2, Q-switched Nd-YAG (short pulses) and long pulses Nd-YAG lasers. The size and density of nanoparticles vary with laser energy, power, pulse duration and the scanning speed of the laser. In this method, MgO nanoparticles were deposited by a laser beam on a quartz substrate from aqueous solution of magnesium nitrate. AFM images reveal formation of small nanoparticle size of 24.5 nm with surface roughness 6.97nm by Q-switched Nd-YAG laser (10 ns) when the energy was 1J. While for CO2 laser, the smallest size was 18.8 nm at 0.4mm/s scanning speed with surface roughness 5.21nm at the same scanning speed. Moreover, long Nd-YAG pulses laser produces relatively larger average size of 37.5nm at 0.8ms pulse duration. The absorption spectra from UV-Visible spectroscopy were also conducted. The best absorption intensity was obtained at a wavelength ranging between 420-430 nm for both lasers. Finally, Thermal analysis using COMSOL Multiphysics software for the deposition process reveals that maximum temperature about 440Kfor Q-Switched Nd-YAG laser at 1J laser energy. While for RF CO2 laser, the maximum temperature obtained at 0.4mm/s scanning speed is 850K.This work provides a good knowledge for the deposition of nanoparticles using laser beams.

Room temperature intrinsic ferromagnetism in pulsed laser ablated few layers of 2D-WS2 on Si/SiO2 substrates

In this work we report the room temperature intrinsic ferromagnetism of pulsed laser deposited few layers of WS2. The ablation was carried out by employing the fourth harmonics of Q-switched Nd-YAG laser (266 nm) at a temperature of 700 °C on Si/SiO2 substrates. Few layers of WS2 were confirmed by Raman and AFM measurements. The photoluminescence spectrum reveals the defect free nature of few layers of WS2 and exhibits intense emission near the band gap. VSM measurements have explored the room temperature intrinsic ferromagnetism in a few layers of WS2 thin films with a saturation magnetisation of 20.1 μemu. This is the first report of intrinsic ferromagnetism in PLD grown few layers of WS2. The room temperature intrinsic ferromagnetic properties in a few layers of two dimensional WS2 can be exploited to design atomically thin spintronic devices.