linq to json

IEnumerable<Employee> empJson = from emp in employees
where emp.Department == "IT Department"
select emp;
DataContractJsonSerializer ser =
new DataContractJsonSerializer(typeof(IEnumerable<Employee>));
MemoryStream ms = new MemoryStream();
ser.WriteObject(ms, empJson);
string json = Encoding.Default.GetString(ms.ToArray());
ms.Close();
Response.Write(json);