Open a PopUp Window on the ASP.NET Button Click event and pass Parameters

Open a PopUp Window
C#

protected void Button1_Click(object sender, EventArgs e)

{

    string queryString =

        "http://localhost:39208/TreeView.aspx?param1=" 

        + TextBox1.Text.Trim();   

    string newWin = 

        "window.open('" + queryString + "');";

    ClientScript.RegisterStartupScript(this.GetType(), "pop", newWin, true);

}